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jsconfig.json option

noImplicitThis

  • Default false
  • Since TypeScript 2.0

Inside a plain function, this depends on how the function is called, so TypeScript often cannot know its type and falls back to any. noImplicitThis reports those uses (TS2683), so a typo in this.nmae cannot slip through.

It is part of strict and arrived with TypeScript 2.0. Methods in classes and object literals are not affected: there this has a known type.

At a glance

Write Leave it to strict; write "noImplicitThis": false only to turn this one check back off
On the command line --noImplicitThis
Type boolean
Default in TypeScript 5.9 false (on when strict is on)
Default from TypeScript 6.0 true, through strict (TypeScript 6.0)
TypeScript's description Enable error reporting when 'this' is given the type 'any'.

The description is quoted from TypeScript's own option list (Apache-2.0); see the notices.

Examples

main.js Error confirmed 5.9.3 TypeScript 5.9.3, run 21 October 2026: main.js(5,13): error TS2683: 'this' implicitly has type 'any' because it does not have a type annotation. main.js(5,32): error TS2683: 'this' implicitly has type 'any' because it does not have a type annotation. 6.0.3 TypeScript 6.0.3, run 21 October 2026: the same as 5.9.3. main.js(5,13): error TS2683: 'this' implicitly has type 'any' because it does not have a type annotation. main.js(5,32): error TS2683: 'this' implicitly has type 'any' because it does not have a type annotation. 7.0.2 TypeScript 7.0.2, run 21 October 2026: the same as 5.9.3. main.js(5,13): error TS2683: 'this' implicitly has type 'any' because it does not have a type annotation. main.js(5,32): error TS2683: 'this' implicitly has type 'any' because it does not have a type annotation. checked 21 October 2026 
export const product = { name: "Tea", price: 3, describe };

function describe() {
  return `${this.name} costs ${this.price}`;error TS2683: 'this' implicitly has type 'any' because it does not have a type annotation.error TS2683: 'this' implicitly has type 'any' because it does not have a type annotation.
}
noImplicitThis on: this has no known type in a plain function.
jsconfig.json for this example 
{
  "compilerOptions": {
    "checkJs": true,
    "noEmit": true,
    "strict": true,
    "target": "es2022",
    "module": "nodenext",
    "types": []
  },
  "include": [
    "*.js"
  ]
}
main.js TypeScript 5.9.3 TypeScript 5.9.3, run 21 October 2026: No errors. 6.0.3 TypeScript 6.0.3, run 21 October 2026: the same as 5.9.3. No errors. 7.0.2 TypeScript 7.0.2, run 21 October 2026: the same as 5.9.3. No errors. checked 21 October 2026 
export const product = { name: "Tea", price: 3, describe };

function describe() {
  return `${this.name} costs ${this.price}`;
}
noImplicitThis off: this is any.
jsconfig.json for this example 
{
  "compilerOptions": {
    "checkJs": true,
    "noEmit": true,
    "strict": true,
    "target": "es2022",
    "module": "nodenext",
    "types": [],
    "noImplicitThis": false
  },
  "include": [
    "*.js"
  ]
}

Saying what this is

Add a @this tag, /** @this {{ name: string, price: number }} */, or move the function into the object or class as a method, where this is typed for you.

Gotchas

  • A function that assigns to this.something is treated as a constructor function in a .js file, so its this is the instance and is never reported.
  • Arrow functions take this from where they are written, so they are never the cause.

  • JSDoc tag

    @this

    The JSDoc @this tag gives this a type inside a function, such as an event handler, and makes TypeScript check every call for that this. Syntax and examples.

  • Type expression

    this parameters

    A this parameter types this inside a function. In JSDoc, write it first in a function type, (this: HTMLInputElement) => void, or use @this on a declaration.

  • jsconfig.json option

    strict

    strict turns on the strict type-checking family with one switch: nine options in TypeScript 5.9. What each catches in a .js file, and how to turn one back off.

  • jsconfig.json option

    strictBindCallApply

    strictBindCallApply checks the arguments you pass through bind, call and apply against the function's own parameters, instead of accepting anything.

  • TypeScript error

    TS2683: this has no type in a plain function

    TS2683 means a function that is not a method uses this, so the checker does not know what this is. Declare it with @this, or use event.currentTarget.

Sources

Last reviewed 20 October 2026.