TypeScript Config option

The tsconfig option allows you to define which tsconfig JSON file to use. An inline compiler options object can also be specified instead of a file path.

By default ts-jest will try to find a tsconfig.json in your project. If it cannot find one, it will use the default TypeScript compiler options; except, ES2015 is used as target instead of ES5.

If you need to use defaults and force ts-jest to use the defaults even if there is a tsconfig.json in your project, you can set this option to false.

Examples

Path to a tsconfig file

The path should be relative to the current working directory where you start Jest from. You can also use <rootDir> in the path to start from the project root dir.

jest.config.ts

import type { Config } from 'jest'

const jestConfig: JestConfigWithTsJest = {
  // [...]
  transform: {
    // '^.+\\.[tj]sx?$' to process ts,js,tsx,jsx with `ts-jest`
    // '^.+\\.m?[tj]sx?$' to process ts,js,tsx,jsx,mts,mjs,mtsx,mjsx with `ts-jest`
    '^.+\\.tsx?$': [
      'ts-jest',
      {
        tsconfig: 'tsconfig.test.json',
      },
    ],
  },
}

export default jestConfig

Inline compiler options

Refer to the TypeScript compiler options for reference. It's basically the same object you'd put in your tsconfig.json's compilerOptions.

jest.config.ts

import type { Config } from 'jest'

const jestConfig: Config = {
  // [...]
  transform: {
    // '^.+\\.[tj]sx?$' to process ts,js,tsx,jsx with `ts-jest`
    // '^.+\\.m?[tj]sx?$' to process ts,js,tsx,jsx,mts,mjs,mtsx,mjsx with `ts-jest`
    '^.+\\.tsx?$': [
      'ts-jest',
      {
        tsconfig: {
          importHelpers: true,
        },
      },
    ],
  },
}

export default jestConfig

Disable auto-lookup

By default ts-jest will try to find a tsconfig.json in your project. But you may not want to use it at all and keep TypeScript default options. You can achieve this by setting tsconfig to false.

jest.config.ts

import type { Config } from 'jest'

const jestConfig: Config = {
  // [...]
  transform: {
    // '^.+\\.[tj]sx?$' to process ts,js,tsx,jsx with `ts-jest`
    // '^.+\\.m?[tj]sx?$' to process ts,js,tsx,jsx,mts,mjs,mtsx,mjsx with `ts-jest`
    '^.+\\.tsx?$': [
      'ts-jest',
      {
        tsconfig: false,
      },
    ],
  },
}

export default jestConfig