TypeScript, a superset of JavaScript, has gained significant popularity among developers for its ability to catch errors during the development process and enhance the overall reliability and maintainability of codebases. Like any programming language, TypeScript comes equipped with a rich set of error codes that assist developers in identifying and resolving issues within their code.
In this comprehensive guide, we delve into the world of TypeScript error codes, shedding light on their importance and providing explanations to help you better understand and troubleshoot common errors. Whether you’re a seasoned TypeScript developer or just getting started, this article aims to equip you with the knowledge and insights to navigate the intricacies of TypeScript error codes.
By familiarizing ourselves with the various error codes encountered in TypeScript, we gain the ability to interpret the error messages presented by the compiler and promptly address potential pitfalls in our code. Each error code represents a distinct issue that the TypeScript compiler identifies, highlighting areas where our code may deviate from the language’s syntax, type system, or best practices.
Throughout this guide, we’ll explore a wide range of TypeScript error codes, discussing their implications, possible causes, and suggested solutions. We’ll cover errors related to type compatibility, variable declarations, function signatures, module imports, control flow statements, and more. By examining these error codes, we can deepen our understanding of TypeScript’s nuances and unleash the full potential of the language.
It’s important to note that the aim of this guide is not to provide an exhaustive list of all TypeScript error codes, but rather to offer a comprehensive overview of common error scenarios and their respective error codes. By grasping the underlying principles behind these errors, you’ll be better equipped to troubleshoot issues, write cleaner code, and harness the full power of TypeScript.
So, whether you’re seeking to improve your TypeScript skills, enhance code quality, or simply gain a better understanding of how TypeScript’s type system works, this guide serves as a valuable resource. Let’s embark on this journey together, demystifying TypeScript error codes and empowering ourselves to write robust, error-free code in the process.
List of error codes in typescript
| Error Code | Explanation |
|---|---|
| 1. TS1001 | Unexpected token. This error occurs when an unexpected symbol or character is encountered in the code, such as a missing semicolon or a typo in a keyword. Check the affected line and correct the syntax error. |
| 2. TS1002 | Unterminated string. This error indicates that a string literal is missing its closing quotation mark. Make sure all strings have proper opening and closing quotes. |
| 3. TS1003 | Identifier expected. This error occurs when a valid identifier (variable or function name) is missing in the code. Ensure that all statements and expressions refer to existing identifiers. |
| 4. TS1004 | This keyword cannot be used in a module. The ‘this’ keyword refers to the current object in a class or method context. However, it cannot be used in a module context. Remove or replace the ‘this’ keyword accordingly. |
| 5. TS1005 | ‘;’ expected. This error occurs when a semicolon is missing at the end of a statement. Check the affected line and add the missing semicolon. |
| 6. TS1006 | Identifier expected. This error is similar to TS1003 but specifically occurs when an identifier is expected but not found. Double-check the line in question and ensure that an identifier is provided where required. |
| 7. TS1007 | Cannot import modules using this construct. TypeScript modules cannot be imported using certain constructs, such as ‘import * as namespace’. Use a valid import statement or an alternative approach. |
| 8. TS1008 | Unexpected token. This error typically occurs when an unexpected character or token is encountered in the code. Review the affected line and check for any unexpected characters or tokens. |
| 9. TS1009 | Unterminated regular expression literal. This error occurs when a regular expression literal is missing its closing delimiter. Ensure that all regular expressions have proper opening and closing delimiters. |
| 10. TS1010 | Unexpected character. This error indicates that an unexpected character has been encountered in the code. Review the affected line and check for any misplaced or incorrect characters. |
| 11. TS1011 | An element access expression should take an argument. This error occurs when an element access expression, such as array indexing, is missing an argument. Provide the required argument for the element access expression. |
| 12. TS1012 | Rest parameter must be last in a parameter list. Rest parameters, denoted by the spread operator (…), should be the last parameter in a function’s parameter list. Rearrange the parameters so that the rest parameter is the last one. |
| 13. TS1013 | A constructor must be a member function of the class. Constructors in TypeScript should be declared as member functions of a class. Ensure that the constructor is declared correctly within the class. |
| 14. TS1014 | A rest parameter must be of an array type. Rest parameters in TypeScript should have an array type annotation. Make sure the rest parameter is declared with an appropriate array type. |
| 15. TS1015 | The return type of a function or method must be either void or a promise. Functions or methods in TypeScript must have a return type annotation of either ‘void’ or a promise type. Add a return type annotation to the function or method. |
| 16. TS1016 | A rest element must be of an array type. Rest elements in TypeScript should have an array type annotation. Make sure the rest element is declared with an appropriate array type. |
| 17. TS1017 | An index signature parameter cannot have a rest modifier. Index signature parameters in TypeScript cannot have the rest modifier (spread operator). Remove the rest modifier from the index signature parameter. |
| 18. TS1018 | A rest element must be the last element in a tuple type. Rest elements, denoted by the spread operator (…), should be the last element in a tuple type. Rearrange the elements so that the rest element is the last one. |
| 19. TS1019 | The name of a declaration must be provided. This error occurs when a declaration is missing its name. Provide a name for the declaration. |
| 20. TS1020 | Parameters cannot appear after rest parameter. Rest parameters, denoted by the spread operator (…), should be the last parameter in a function’s parameter list. Move any parameters that appear after the rest parameter to before it. |
| 21. TS1021 | Duplicate function implementation. This error occurs when multiple implementations of a function are found. Remove or refactor the duplicate implementations to resolve the error. |
| 22. TS1022 | Static methods cannot reference class type parameters. Static methods in TypeScript cannot reference the class type parameters. Remove the reference to the class type parameter in the static method. |
| 23. TS1023 | An enum member cannot have a numeric name. Enum members in TypeScript cannot have a numeric name. Use a non-numeric name for the enum member. |
| 24. TS1024 | Cannot find name ‘{name}’. This error occurs when TypeScript cannot find a declared name. Make sure the name is declared or imported properly. |
| 25. TS1025 | An export assignment cannot be used in a module with other exported elements. Export assignments in TypeScript cannot be used alongside other exported elements within a module. Use either export assignments or named exports, but not both together. |
| 26. TS1026 | An accessor cannot be declared in an ambient context. Accessors (getters and setters) in TypeScript cannot be declared in an ambient context. Remove the accessor declaration from the ambient context. |
| 27. TS1027 | Parameter declaration expected. This error occurs when a parameter declaration is missing in a function or method. Add the required parameter declaration to the function or method. |
| 28. TS1028 | The operand of a delete operator must be optional. The delete operator in TypeScript can only be used with optional properties. Make sure the operand of the delete operator is an optional property. |
| 29. TS1029 | A class can only implement an object type or intersection of object types with statically known members. When implementing interfaces or extended classes, TypeScript requires the class to implement an object type or an intersection of object types with statically known members. Ensure that the class implements the appropriate types. |
| 30. TS1030 | Generic type ‘{type}’ requires between {min} and {max} type arguments. This error occurs when a generic type is used without the required number of type arguments. Provide the correct number of type arguments within the specified range. |
| 31. TS1031 | ‘async’ modifier cannot be used in a constructor declaration. The ‘async’ modifier cannot be used with a constructor in TypeScript. Remove the ‘async’ modifier from the constructor declaration. |
| 32. TS1032 | Code block in ambient context. This error occurs when a code block is found in an ambient context, such as within an ambient declaration or interface. Remove the code block from the ambient context. |
| 33. TS1033 | ‘{name}’ cannot be used as a value because it was imported using ‘import =’. This error occurs when a value imported using ‘import =’ cannot be used as a value. Use the imported value as a namespace or type instead. |
| 34. TS1034 | Variable ‘{name}’ is used before being assigned. This error occurs when a variable is used before it has been assigned a value. Assign a value to the variable before using it. |
| 35. TS1035 | ‘{name}’ is not a namespace. This error occurs when a name that is not a namespace is used as if it were a namespace. Use the correct namespace or remove the namespace reference. |
| 36. TS1036 | Statements are not allowed in ambient contexts. Statements, such as control flow statements or assignments, are not allowed in ambient contexts. Remove the statements from the ambient context. |
| 37. TS1037 | Cannot use ‘new’ with an expression whose type lacks a call or construct signature. This error occurs when the ‘new’ keyword is used with an expression that does not have a call or construct signature. Use the ‘new’ keyword with a constructible expression. |
| 38. TS1038 | A ‘const’ initializer in an ambient context must be a string or numeric literal. In an ambient context, ‘const’ initializers must be string or numeric literals. Use a string or numeric literal as the ‘const’ initializer. |
| 39. TS1039 | Initializers are not allowed in ambient contexts. Initializers, such as variable or property initializers, are not allowed in ambient contexts. Remove the initializers from the ambient context. |
| 40. TS1040 | Duplicate identifier ‘{name}’. This error occurs when multiple declarations of the same identifier are found. Rename or remove the duplicate identifiers to resolve the error. |
| 41. TS1041 | A rest parameter or binding pattern may not be followed by a binding element with an initializer. Rest parameters or binding patterns cannot be followed by binding elements with initializers. Remove the initializer or adjust the syntax accordingly. |
| 42. TS1042 | Cannot use ‘new’ with an expression whose type lacks a call or construct signature. This error occurs when the ‘new’ keyword is used with an expression that does not have a call or construct signature. Use the ‘new’ keyword with a constructible expression. |
| 43. TS1043 | The return type ‘{type}’ of an async function or method must be a promise-like type. Async functions or methods in TypeScript must have a return type that is a promise-like type. Specify the appropriate promise-like type as the return type. |
| 44. TS1044 | A ‘const’ initializer must be a string, numeric, boolean, or enum literal. ‘const’ initializers must be string, numeric, boolean, or enum literals. Use a valid literal type as the ‘const’ initializer. |
| 45. TS1045 | An accessor cannot have a rest parameter. Accessors (getters and setters) in TypeScript cannot have rest parameters. Remove the rest parameter from the accessor. |
| 46. TS1046 | Top-level declarations in ‘.d.ts’ files can only be ambient or TypeScript modules. Top-level declarations in ‘.d.ts’ files can only be ambient or TypeScript modules. Ensure that the top-level declarations in ‘.d.ts’ files follow the correct syntax. |
| 47. TS1047 | A rest parameter cannot have an initializer. Rest parameters, denoted by the spread operator (…), cannot have initializers. Remove the initializer from the rest parameter. |
| 48. TS1048 | A ‘break’ statement can only be used within an enclosing iteration or switch statement. The ‘break’ statement in TypeScript can only be used within an enclosing iteration (loop) or switch statement. Place the ‘break’ statement within the appropriate enclosing statement. |
| 49. TS1049 | A ‘continue’ statement can only be used within an enclosing iteration statement. The ‘continue’ statement in TypeScript can only be used within an enclosing iteration (loop) statement. Place the ‘continue’ statement within the appropriate enclosing statement. |
| 50. TS1050 | A ‘return’ statement can only be used within a function body. The ‘return’ statement in TypeScript can only be used within a function body. Place the ‘return’ statement within the body of a function. |
| 51. TS1051 | Type parameters cannot appear on a constructor declaration. Type parameters cannot be used on a constructor declaration in TypeScript. Remove the type parameters from the constructor declaration. |
| 52. TS1052 | Cannot find name ‘{name}’. This error occurs when TypeScript cannot find a declared name. Make sure the name is declared or imported properly. |
| 53. TS1053 | ‘this’ cannot be referenced in an ambient context. The ‘this’ keyword cannot be referenced in an ambient context, such as within an ambient declaration or interface. Remove the reference to ‘this’ from the ambient context. |
| 54. TS1054 | A ‘const’ initializer must be a string, numeric, boolean, enum, or null literal. ‘const’ initializers must be string, numeric, boolean, enum, or null literals. Use a valid literal type as the ‘const’ initializer. |
| 55. TS1055 | An ambient enum declaration can only be used in global ambient modules. Ambient enum declarations in TypeScript can only be used in global ambient modules. Place the ambient enum declaration in a global ambient module. |
| 56. TS1056 | Accessors are only available when targeting ECMAScript 5 and higher. Accessors (getters and setters) in TypeScript are only available when targeting ECMAScript 5 and higher. Update the target version in your TypeScript configuration. |
| 57. TS1057 | An async function or method must have a valid awaitable return type. Async functions or methods in TypeScript must have a valid awaitable return type. Specify a valid return type that can be awaited. |
| 58. TS1058 | Unexpected token. This error occurs when an unexpected token or character is encountered in the code. Review the affected line and check for any misplaced or incorrect tokens or characters. |
| 59. TS1059 | Duplicate identifier ‘{name}’. This error occurs when multiple declarations of the same identifier are found. Rename or remove the duplicate identifiers to resolve the error. |
| 60. TS1060 | The ‘new’ expression, whose target lacks a construct signature, implicitly has an ‘any’ type. The ‘new’ expression in TypeScript requires a construct signature on its target. Add a construct signature or provide a type annotation for the target. |
| 61. TS1061 | The expression of an ‘export default’ must be an identifier or an assignment to an identifier. The expression of an ‘export default’ statement in TypeScript must be an identifier or an assignment to an identifier. Use a valid identifier or assignment in the ‘export default’ statement. |
| 62. TS1062 | An accessor cannot have type parameters. Accessors (getters and setters) in TypeScript cannot have type parameters. Remove the type parameters from the accessor. |
| 63. TS1063 | An async function or method cannot have a ‘void’ return type. Async functions or methods in TypeScript cannot have a ‘void’ return type. Use ‘void’ only when the function or method is not asynchronous. |
| 64. TS1064 | Invalid ‘extends’ clause: Types have separate declarations of a private property ‘{property}’. The ‘extends’ clause in a TypeScript class cannot have types with separate declarations of a private property. Ensure that the private property is declared correctly in the extended class. |
| 65. TS1065 | Unexpected character. This error occurs when an unexpected character is encountered in the code. Review the affected line and check for any misplaced or incorrect characters. |
| 66. TS1066 | The element implicitly has an ‘any’ type because expression of type ‘{type}’ can’t be used to index type ‘{type}’. The element implicitly has an ‘any’ type in TypeScript because the expression used to index a type cannot be validated. Ensure that the indexing expression is of a compatible type. |
| 67. TS1067 | Implicit use of ‘any’ type. This error occurs when the TypeScript compiler cannot determine the type of a variable or expression, and it defaults to the ‘any’ type. Provide explicit type annotations to resolve the error. |
| 68. TS1068 | Unexpected token. This error occurs when an unexpected token or character is encountered in the code. Review the affected line and check for any misplaced or incorrect tokens or characters. |
| 69. TS1069 | ‘{name}’ cannot be used as a namespace. This error occurs when a name that cannot be used as a namespace is referenced as one. Use a valid namespace or remove the namespace reference. |
| 70. TS1070 | A ‘super’ call must be the first statement in the constructor when a class contains initialized properties or has parameter properties. A ‘super’ call in a constructor must be the first statement when a class contains initialized properties or parameter properties. Move the ‘super’ call to the beginning of the constructor. |
| 71. TS1071 | ‘{name}’ cannot be modified because it is not a variable. This error occurs when an attempt is made to modify a value that is not a variable. Ensure that the value being modified is a variable. |
| 72. TS1072 | ‘{name}’ cannot be modified because it is a read-only property. This error occurs when an attempt is made to modify a read-only property. Ensure that the property being modified is not marked as read-only. |
| 73. TS1073 | An accessor cannot have type arguments. Accessors (getters and setters) in TypeScript cannot have type arguments. Remove the type arguments from the accessor. |
| 74. TS1074 | ‘{name}’ is referenced directly or indirectly in its own initializer. This error occurs when a variable or constant is referenced within its own initializer. Use a different variable or adjust the initializer to avoid self-reference. |
| 75. TS1075 | A ‘{name}’ property initializer is only allowed in a constructor or in a default value. Property initializers, denoted by the equals sign (=), are only allowed in a constructor or as default values. Move the property initializer to the constructor or use a default value. |
| 76. TS1076 | A computed property name must be of type ‘string’, ‘number’, ‘symbol’, or ‘any’. Computed property names in TypeScript must be of type ‘string’, ‘number’, ‘symbol’, or ‘any’. Ensure that the computed property name matches the valid types. |
| 77. TS1077 | The type of a ‘break’ expression must be ‘never’ or ‘void’. The type of a ‘break’ expression in TypeScript must be ‘never’ or ‘void’. Make sure the ‘break’ expression is used in the appropriate context. |
| 78. TS1078 | A ‘return’ statement with a value can only be used within a function body. A ‘return’ statement with a value in TypeScript can only be used within a function body. Place the ‘return’ statement within the body of a function. |
| 79. TS1079 | Property or signature expected. This error occurs when a property or signature is expected but not found. Check the affected line and ensure that a property or signature is provided where required. |
| 80. TS1080 | The type of a ‘continue’ expression must be ‘never’ or ‘void’. The type of a ‘continue’ expression in TypeScript must be ‘never’ or ‘void’. Make sure the ‘continue’ expression is used in the appropriate context. |
| 81. TS1081 | Cannot assign to ‘{name}’ because it is a read-only property. This error occurs when an attempt is made to assign a value to a read-only property. Ensure that the property being assigned is not marked as read-only. |
| 82. TS1082 | Unexpected token. This error occurs when an unexpected token or character is encountered in the code. Review the affected line and check for any misplaced or incorrect tokens or characters. |
| 83. TS1083 | ‘{name}’ is not a valid type argument. This error occurs when an invalid type argument is provided. Use a valid type argument that matches the expected type. |
| 84. TS1084 | Invalid ‘new.target’ expression. ‘new.target’ expressions in TypeScript must be valid and match the expected syntax. Review the ‘new.target’ expression and ensure it is correct. |
| 85. TS1085 | Unexpected token. This error occurs when an unexpected token or character is encountered in the code. Review the affected line and check for any misplaced or incorrect tokens or characters. |
| 86. TS1086 | An accessor cannot have a ‘get’ and ‘set’ accessor with different types. Accessors (getters and setters) in TypeScript cannot have different types. Ensure that the types of the ‘get’ and ‘set’ accessors match. |
| 87. TS1087 | An async function or method must have a valid return type. Async functions or methods in TypeScript must have a valid return type. Specify a valid return type for the async function or method. |
| 88. TS1088 | Cannot use an index signature to index type ‘{type}’. This error occurs when an index signature is used to index a type that does not have one. Check the type being indexed and ensure that it has an index signature. |
| 89. TS1089 | Duplicate identifier ‘{name}’. This error occurs when multiple declarations of the same identifier are found. Rename or remove the duplicate identifiers to resolve the error. |
| 90. TS1090 | ‘{name}’ is referenced directly or indirectly in its own type annotation. This error occurs when a type annotation references itself directly or indirectly. Ensure that the type annotation does not create a circular reference. |
| 91. TS1091 | ‘{name}’ is not a function. This error occurs when a value that is not a function is used as a function. Check the value being used and ensure that it is a function. |
| 92. TS1092 | ‘{name}’ must be of type ‘symbol’, but here has type ‘{type}’. This error occurs when a value is expected to be of type ‘symbol’ but has a different type. Make sure the value is of the correct type. |
| 93. TS1093 | An accessor cannot have a ‘get’ and ‘set’ accessor in the same declaration. Accessors (getters and setters) in TypeScript cannot have both ‘get’ and ‘set’ accessors in the same declaration. Separate them into distinct accessors. |
| 94. TS1094 | An accessor cannot have a ‘get’ and ‘set’ accessor with different accessibility modifiers. Accessors (getters and setters) in TypeScript cannot have different accessibility modifiers. Ensure that the accessibility modifiers of the ‘get’ and ‘set’ accessors match. |
| 95. TS1095 | An accessor cannot have an implementation. Accessors (getters and setters) in TypeScript cannot have an implementation. Remove the implementation from the accessor. |
| 96. TS1096 | Expression of type ‘{type}’ cannot be used to index type ‘{type}’. This error occurs when an expression of an invalid type is used to index a type. Check the expression being used and ensure that it is of the correct type. |
| 97. TS1097 | Property assignment expected. This error occurs when a property assignment is expected but not found. Check the affected line and ensure that a property assignment is provided where required. |
| 98. TS1098 | Expression produces a union type that is too complex to represent. This error occurs when an expression produces a union type that is too complex to be represented. Simplify the expression or type to avoid the error. |
| 99. TS1099 | Expression of type ‘{type}’ lacks a call signature. This error occurs when an expression of a type without a call signature is used as a function. Check the type of the expression and ensure it has a valid call signature. |
| 100. TS1100 | Unexpected token. This error occurs when an unexpected token or character is encountered in the code. Review the affected line and check for any misplaced or incorrect tokens or characters. |
| Error Code | Explanation |
|---|---|
| 101. TS1101 | Invalid type assertion. This error occurs when a type assertion is used with an incompatible type. Verify that the type assertion is compatible with the type being asserted. |
| 102. TS1102 | An import declaration cannot refer to an external module declaration. Import declarations in TypeScript cannot refer to external module declarations. Use a valid import statement or reference the external module declaration correctly. |
| 103. TS1103 | ‘{name}’ is declared but its value is never read. This error occurs when a declared variable or constant is never read or used in the code. Remove the declaration or make sure the variable or constant is used appropriately. |
| 104. TS1104 | Cannot find name ‘{name}’. This error occurs when TypeScript cannot find a declared name. Make sure the name is declared or imported properly. |
| 105. TS1105 | An async function or method must have a valid ‘await’ expression. Async functions or methods in TypeScript must have a valid ‘await’ expression. Ensure that the ‘await’ expression is used correctly within the async function or method. |
| 106. TS1106 | ‘{name}’ is not assignable to type ‘{type}’. This error occurs when a value is assigned to a variable or parameter that is not compatible with the expected type. Verify the compatibility between the value and the type, and adjust the assignment accordingly. |
| 107. TS1107 | Invalid left-hand side of assignment expression. This error occurs when the left-hand side of an assignment expression is not a valid target for assignment. Verify that the target of the assignment is valid. |
| 108. TS1108 | The ‘this’ context of type ‘{type}’ is not assignable to method’s ‘this’ of type ‘{type}’. This error occurs when the ‘this’ context of a method is not compatible with the expected ‘this’ type. Adjust the method’s ‘this’ type or ensure that the correct ‘this’ context is used when invoking the method. |
| 109. TS1109 | An object literal cannot have multiple properties with the same name. This error occurs when an object literal contains multiple properties with the same name. Remove or rename the duplicate properties in the object literal. |
| 110. TS1110 | Type ‘{type}’ is not assignable to type ‘{type}’. This error occurs when a type is not assignable to another type. Check the type compatibility and adjust the assignment or type annotations accordingly. |
| 111. TS1111 | Type expected. This error occurs when a type is expected but not provided. Ensure that the required type is specified in the appropriate location. |
| 112. TS1112 | An import declaration can only refer to a module. Import declarations in TypeScript can only refer to modules. Verify that the import declaration refers to a valid module. |
| 113. TS1113 | An async function or method must have a valid return type. Async functions or methods in TypeScript must have a valid return type. Specify a valid return type for the async function or method. |
| 114. TS1114 | ‘{name}’ is referenced directly or indirectly in its own initializer. This error occurs when a variable or constant is referenced within its own initializer. Use a different variable or adjust the initializer to avoid self-reference. |
| 115. TS1115 | Invalid expression. This error occurs when an expression is not valid or has incorrect syntax. Review the affected expression and correct any errors. |
| 116. TS1116 | ‘{name}’ is not assignable to the constraint of type parameter ‘{type}’. This error occurs when a type does not satisfy the constraint of a type parameter. Ensure that the type being assigned satisfies the constraint. |
| 117. TS1117 | An object literal cannot have any properties. This error occurs when an object literal is defined without any properties. Add properties to the object literal or remove it if not needed. |
| 118. TS1118 | Type expected. This error occurs when a type is expected but not provided. Ensure that the required type is specified in the appropriate location. |
| 119. TS1119 | Cannot assign to ‘{name}’ because it is a read-only property. This error occurs when an attempt is made to assign a value to a read-only property. Ensure that the property being assigned is not marked as read-only. |
| 120. TS1120 | An async function or method must have a valid ‘await’ expression. Async functions or methods in TypeScript must have a valid ‘await’ expression. Ensure that the ‘await’ expression is used correctly within the async function or method. |
| 121. TS1121 | Cannot reference a type that is being defined. This error occurs when a type references itself during its own definition. Resolve the circular reference in the type definition. |
| 122. TS1122 | ‘{name}’ is not a function or method. This error occurs when a value that is not a function or method is used as one. Verify the value being used and ensure that it is a function or method. |
| 123. TS1123 | Accessors are only available when targeting ECMAScript 5 and higher. Accessors (getters and setters) in TypeScript are only available when targeting ECMAScript 5 and higher. Update the target version in your TypeScript configuration. |
| 124. TS1124 | ‘{name}’ is declared but its value is never used. This error occurs when a declared variable or constant is never used in the code. Remove the declaration or make sure the variable or constant is used appropriately. |
| 125. TS1125 | An object literal cannot have any properties. This error occurs when an object literal is defined without any properties. Add properties to the object literal or remove it if not needed. |
| 126. TS1126 | Declaration expected. This error occurs when a declaration is expected but not found. Check the syntax and ensure that a valid declaration is provided. |
| 127. TS1127 | An async function or method must have a valid ‘await’ expression. Async functions or methods in TypeScript must have a valid ‘await’ expression. Ensure that the ‘await’ expression is used correctly within the async function or method. |
| 128. TS1128 | Declaration or statement expected. This error occurs when a declaration or statement is expected but not found. Check the syntax and ensure that a valid declaration or statement is provided. |
| 129. TS1129 | Expression expected. This error occurs when an expression is expected but not found. Check the syntax and ensure that a valid expression is provided. |
| 130. TS1130 | Parameter ‘{name}’ implicitly has an ‘{type}’ type. This error occurs when a function parameter is implicitly assigned a type based on its usage. Add an explicit type annotation to the parameter to resolve the error. |
| 131. TS1131 | Property ‘{name}’ does not exist on type ‘{type}’. This error occurs when a property is accessed on a type that does not have that property. Verify the type and ensure that the property exists on it. |
| 132. TS1132 | Property ‘{name}’ is missing in type ‘{type}’. This error occurs when a required property is missing in an object type. Add the missing property to the object or adjust the type annotation accordingly. |
| 133. TS1133 | The right-hand side of an arithmetic operation must be of type ‘any’, ‘number’, ‘bigint’, or an enum type. The right-hand side of an arithmetic operation in TypeScript must be of type ‘any’, ‘number’, ‘bigint’, or an enum type. Ensure that the right-hand side of the operation matches one of these types. |
| 134. TS1134 | Property ‘{name}’ is protected and only accessible within the class ‘{class}’. This error occurs when an attempt is made to access a protected property outside the class it is defined in. Access the protected property within the appropriate class or adjust its accessibility if necessary. |
| 135. TS1135 | Argument expression expected. This error occurs when an argument expression is expected but not found. Check the syntax and ensure that a valid argument expression is provided. |
| 136. TS1136 | Property ‘{name}’ does not exist on type ‘{type}’. This error occurs when a property is accessed on a type that does not have that property. Verify the type and ensure that the property exists on it. |
| 137. TS1137 | Object literal may only specify known properties. This error occurs when an object literal contains unknown or non-existent properties. Ensure that the object literal only specifies known properties or use a type assertion to bypass the type checking. |
| 138. TS1138 | Type parameter ‘{name}’ cannot be referenced in a computed property name. This error occurs when a type parameter is referenced in a computed property name. Computed property names in TypeScript cannot reference type parameters. Adjust the computed property name to avoid the reference. |
| 139. TS1139 | Argument of type ‘{type}’ is not assignable to parameter of type ‘{type}’. This error occurs when an argument value is not assignable to the corresponding parameter type. Verify the compatibility between the argument value and the parameter type, and adjust the argument or parameter accordingly. |
| 140. TS1140 | Expression produces a union type that is too complex to represent. This error occurs when an expression produces a union type that is too complex to be represented. Simplify the expression or type to avoid the error. |
| 141. TS1141 | String literal expected. This error occurs when a string literal is expected but not found. Check the syntax and ensure that a valid string literal is provided. |
| 142. TS1142 | A ‘break’ statement can only be used within an enclosing iteration or switch statement. The ‘break’ statement in TypeScript can only be used within an enclosing iteration (loop) or switch statement. Place the ‘break’ statement within the appropriate enclosing statement. |
| 143. TS1143 | Cannot find name ‘{name}’. This error occurs when TypeScript cannot find a declared name. Make sure the name is declared or imported properly. |
| 144. TS1144 | ‘{name}’ refers to a value, but is being used as a type here. This error occurs when a value is used as a type. Ensure that the correct type is used instead of the value. |
| 145. TS1145 | Argument for property ‘{name}’ of type ‘{type}’ is not assignable to parameter of type ‘{type}’. This error occurs when an argument value for a property is not assignable to the corresponding parameter type. Verify the compatibility between the argument value and the parameter type, and adjust the argument or parameter accordingly. |
| 146. TS1146 | Declaration expected. This error occurs when a declaration is expected but not found. Check the syntax and ensure that a valid declaration is provided. |
| 147. TS1147 | ‘{name}’ is declared but never used. This error occurs when a declared variable, constant, function, or import is never used in the code. Remove the declaration or make sure it is used appropriately. |
| 148. TS1148 | Cannot assign to ‘{name}’ because it is a constant or a read-only property. This error occurs when an attempt is made to assign a value to a constant or a read-only property. Ensure that the constant or read-only property is not assigned a new value. |
| 149. TS1149 | A ‘continue’ statement can only be used within an enclosing iteration statement. The ‘continue’ statement in TypeScript can only be used within an enclosing iteration (loop) statement. Place the ‘continue’ statement within the appropriate enclosing statement. |
| 150. TS1150 | The operand of a delete operator must be optional. The delete operator in TypeScript can only be used with optional properties. Make sure the operand of the delete operator is an optional property. |
| 151. TS1151 | An object literal cannot have multiple properties with the same name. This error occurs when an object literal contains multiple properties with the same name. Remove or rename the duplicate properties in the object literal. |
| 152. TS1152 | Decorators are not valid here. This error occurs when decorators are used in an invalid location. Check the usage of decorators and ensure they are used in a valid location, such as preceding a class, method, or property declaration. |
| 153. TS1153 | A ‘super’ call must be the first statement in the constructor when a class contains initialized properties or has parameter properties. A ‘super’ call in a constructor must be the first statement when a class contains initialized properties or parameter properties. Move the ‘super’ call to the beginning of the constructor. |
| 154. TS1154 | An export declaration cannot have modifiers. Export declarations in TypeScript cannot have modifiers such as ‘public’ or ‘private’. Remove the modifiers from the export declaration. |
| 155. TS1155 | ‘{name}’ is declared but its value is never used. This error occurs when a declared variable or constant is never used in the code. Remove the declaration or make sure the variable or constant is used appropriately. |
| 156. TS1156 | Decorators are not valid here. This error occurs when decorators are used in an invalid location. Check the usage of decorators and ensure they are used in a valid location, such as preceding a class, method, or property declaration. |
| 157. TS1157 | An object literal cannot have any properties. This error occurs when an object literal is defined without any properties. Add properties to the object literal or remove it if not needed. |
| 158. TS1158 | The ‘await’ operator can only be used within an async function. The ‘await’ operator in TypeScript can only be used within an async function. Ensure that the ‘await’ operator is used within an async function. |
| 159. TS1159 | A ‘break’ statement can only be used within an enclosing iteration or switch statement. The ‘break’ statement in TypeScript can only be used within an enclosing iteration (loop) or switch statement. Place the ‘break’ statement within the appropriate enclosing statement. |
| 160. TS1160 | A type parameter cannot be used to reference itself directly or indirectly within its own constraint. This error occurs when a type parameter references itself directly or indirectly within its own constraint. Resolve the circular reference in the type parameter’s constraint. |
| 161. TS1161 | A ‘const’ initializer must be a string, numeric, boolean, enum, or null literal. ‘const’ initializers must be string, numeric, boolean, enum, or null literals. Use a valid literal type as the ‘const’ initializer. |
| 162. TS1162 | An object literal cannot have any properties. This error occurs when an object literal is defined without any properties. Add properties to the object literal or remove it if not needed. |
| 163. TS1163 | A computed property name must be of type ‘string’, ‘number’, ‘symbol’, or ‘any’. Computed property names in TypeScript must be of type ‘string’, ‘number’, ‘symbol’, or ‘any’. Ensure that the computed property name matches the valid types. |
| 164. TS1164 | Computed property names are not allowed in enums. Computed property names in TypeScript are not allowed in enums. Use string literals or numeric literals as the property names in enums. |
| 165. TS1165 | A ‘continue’ statement can only be used within an enclosing iteration statement. The ‘continue’ statement in TypeScript can only be used within an enclosing iteration (loop) statement. Place the ‘continue’ statement within the appropriate enclosing statement. |
| 166. TS1166 | An object literal cannot have multiple properties with the same name. This error occurs when an object literal contains multiple properties with the same name. Remove or rename the duplicate properties in the object literal. |
| 167. TS1167 | A ‘return’ statement can only be used within a function body. A ‘return’ statement in TypeScript can only be used within a function body. Place the ‘return’ statement within the body of a function. |
| 168. TS1168 | An async function or method cannot have a ‘void’ return type. Async functions or methods in TypeScript cannot have a ‘void’ return type. Use ‘void’ only when the function or method is not asynchronous. |
| 169. TS1169 | A computed property name must be of type ‘string’, ‘number’, ‘symbol’, or ‘any’. Computed property names in TypeScript must be of type ‘string’, ‘number’, ‘symbol’, or ‘any’. Ensure that the computed property name matches the valid types. |
| 170. TS1170 | Property ‘{name}’ of exported interface has or is using private name ‘{name}’. This error occurs when an exported interface references a private name. Ensure that the interface only references public or exported names. |
| 171. TS1171 | An object literal cannot have multiple properties with the same name. This error occurs when an object literal contains multiple properties with the same name. Remove or rename the duplicate properties in the object literal. |
| 172. TS1172 | A ‘break’ statement can only be used within an enclosing iteration or switch statement. The ‘break’ statement in TypeScript can only be used within an enclosing iteration (loop) or switch statement. Place the ‘break’ statement within the appropriate enclosing statement. |
| 173. TS1173 | The ‘await’ operator can only be used within an async function. The ‘await’ operator in TypeScript can only be used within an async function. Ensure that the ‘await’ operator is used within an async function. |
| 174. TS1174 | ‘{name}’ is not assignable to type ‘{type}’. This error occurs when a value is assigned to a variable or parameter that is not compatible with the expected type. Verify the compatibility between the value and the type, and adjust the assignment accordingly. |
| 175. TS1175 | An async function or method must have a valid ‘await’ expression. Async functions or methods in TypeScript must have a valid ‘await’ expression. Ensure that the ‘await’ expression is used correctly within the async function or method. |
| 176. TS1176 | A computed property name must be of type ‘string’, ‘number’, ‘symbol’, or ‘any’. Computed property names in TypeScript must be of type ‘string’, ‘number’, ‘symbol’, or ‘any’. Ensure that the computed property name matches the valid types. |
| 177. TS1177 | Cannot assign to ‘{name}’ because it is a constant or a read-only property. This error occurs when an attempt is made to assign a value to a constant or a read-only property. Ensure that the constant or read-only property is not assigned a new value. |
| 178. TS1178 | Cannot access ‘{name}’ before initialization. This error occurs when a variable or constant is accessed before it has been assigned a value. Ensure that the variable or constant is initialized before accessing it. |
| 179. TS1179 | A ‘break’ statement can only be used within an enclosing iteration or switch statement. The ‘break’ statement in TypeScript can only be used within an enclosing iteration (loop) or switch statement. Place the ‘break’ statement within the appropriate enclosing statement. |
| 180. TS1180 | A ‘continue’ statement can only be used within an enclosing iteration statement. The ‘continue’ statement in TypeScript can only be used within an enclosing iteration (loop) statement. Place the ‘continue’ statement within the appropriate enclosing statement. |
| 181. TS1181 | Cannot extend an interface ‘{name}’. This error occurs when an interface attempts to extend another interface that is not extendable. Verify that the interface being extended is valid and can be extended. |
| 182. TS1182 | Generic type ‘{name}’ requires {count} type argument(s). This error occurs when a generic type is used without providing the required type arguments. Provide the required type arguments for the generic type. |
| 183. TS1183 | An object literal cannot have multiple properties with the same name. This error occurs when an object literal contains multiple properties with the same name. Remove or rename the duplicate properties in the object literal. |
| 184. TS1184 | The operand of a delete operator must be optional. The delete operator in TypeScript can only be used with optional properties. Make sure the operand of the delete operator is an optional property. |
| 185. TS1185 | ‘{name}’ refers to a value, but is being used as a type here. This error occurs when a value is used as a type. Ensure that the correct type is used instead of the value. |
| 186. TS1186 | Invalid type parameter. This error occurs when a type parameter is invalid or incorrectly specified. Verify the syntax and correctness of the type parameter. |
| 187. TS1187 | Duplicate string index signature. This error occurs when an interface or type contains duplicate string index signatures. Remove the duplicate string index signature to resolve the error. |
| 188. TS1188 | A ‘continue’ statement can only be used within an enclosing iteration statement. The ‘continue’ statement in TypeScript can only be used within an enclosing iteration (loop) statement. Place the ‘continue’ statement within the appropriate enclosing statement. |
| 189. TS1189 | The operand of a delete operator must be optional. The delete operator in TypeScript can only be used with optional properties. Make sure the operand of the delete operator is an optional property. |
| 190. TS1190 | Only public and protected methods of the base class are accessible via the ‘super’ keyword. This error occurs when a method that is not public or protected is accessed using the ‘super’ keyword. Ensure that the method being accessed is public or protected in the base class. |
| 191. TS1191 | Property ‘{name}’ of type ‘{type}’ is not assignable to string index type ‘{type}’. This error occurs when a property with a specific type is not assignable to a string index type. Verify the compatibility between the property type and the string index type, and adjust the property or string index type accordingly. |
| 192. TS1192 | Type ‘{type}’ has no property ‘{name}’ and no string index signature. This error occurs when a type does not have a property with the specified name and does not have a string index signature. Ensure that the property name is correct or add a string index signature to the type. |
| 193. TS1193 | The right-hand side of an arithmetic operation must be of type ‘any’, ‘number’, ‘bigint’, or an enum type. The right-hand side of an arithmetic operation in TypeScript must be of type ‘any’, ‘number’, ‘bigint’, or an enum type. Ensure that the right-hand side of the operation matches one of these types. |
| 194. TS1194 | A computed property name must be of type ‘string’, ‘number’, ‘symbol’, or ‘any’. Computed property names in TypeScript must be of type ‘string’, ‘number’, ‘symbol’, or ‘any’. Ensure that the computed property name matches the valid types. |
| 195. TS1195 | The operand of a delete operator must be optional. The delete operator in TypeScript can only be used with optional properties. Make sure the operand of the delete operator is an optional property. |
| 196. TS1196 | Property ‘{name}’ is missing in type ‘{type}’. This error occurs when a required property is missing in an object type. Add the missing property to the object or adjust the type annotation accordingly. |
| 197. TS1197 | Cannot find module ‘{module}’. This error occurs when TypeScript cannot find a module that is being imported. Verify the module path and ensure that the module is installed and accessible. |
| 198. TS1198 | The ‘this’ context of type ‘{type}’ is not assignable to method’s ‘this’ of type ‘{type}’. This error occurs when the ‘this’ context of a method is not compatible with the expected ‘this’ type. Adjust the method’s ‘this’ type or ensure that the correct ‘this’ context is used when invoking the method. |
| 199. TS1199 | Function lacks ending return statement and return type does not include ‘undefined’. This error occurs when a function does not have a return statement at the end and its return type does not include ‘undefined’. Add a return statement at the end of the function or adjust the return type to include ‘undefined’. |
| 200. TS1200 | Expression expected. This error occurs when an expression is expected but not found. Check the syntax and ensure that a valid expression is provided. |
