TypeScript

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Cypress ships with official type declarations for TypeScript. This allows you to write your tests in TypeScript. All that is required is a little bit of configuration.

Transpiling TypeScript test files

Just as you would when writing TypeScript files in your project, you will have to handle transpiling your TypeScript test files. Cypress exposes a file:preprocessor event you can use to customize how your test code is transpiled and sent to the browser.

Examples

Set up your dev environment

Please refer to your code editor in TypeScript’s Editor Support doc and follow the instructions for your IDE to get TypeScript support and intelligent code completion configured in your developer environment before continuing. TypeScript support is built in for Visual Studio Code, Visual Studio, and WebStorm - all other editors require extra setup.

Configure tsconfig.json

We recommend the following configuration in a tsconfig.json inside your cypress folder.

{
  "compilerOptions": {
    "strict": true,
    "baseUrl": "../node_modules",
    "target": "es5",
    "lib": ["es5", "dom"],
    "types": ["cypress"],
  },
  "include": [
    "**/*.ts"
  ]
}

The "types" will tell the TypeScript compiler to only include type definitions from Cypress. This will address instances where the project also uses @types/chai or @types/jquery. Since Chai and jQuery are namespaces (globals), incompatible versions will cause the package manager (yarn or npm) to nest and include multiple definitions and cause conflicts.