JSON to JavaScript

What Does This Tool Do?

It takes your JSON and wraps it as a JavaScript const variable declaration - since valid JSON is already valid JavaScript object/array literal syntax, the main value is producing a ready-to-paste, properly named constant.

Why Use This Tool?

Useful for quickly turning an API response or config JSON into a mock data file or test fixture constant in a JavaScript/TypeScript project.

How to Use It

1. Paste valid JSON.
2. Enter a variable name for the constant.
3. Copy the generated const declaration into your JS/TS file.

Limitations

This generates a plain JavaScript value - for a typed version (a TypeScript interface describing the shape), see the JSON to TypeScript tool.

Example

JSON from an API:

{"id": 1042, "name": "Asha", "roles": ["editor"]}

with the variable name mockUser becomes:

const mockUser = {
  id: 1042,
  name: 'Asha',
  roles: [
    'editor'
  ]
};

Where It Helps

• Test fixtures for Jest, Vitest or Cypress - paste a real response as a mock.
• Storybook stories and component demos that need realistic data.
• Prototypes that use hard-coded data before an API exists.

Tips

• Add export in front to share the constant between files: export const mockUser = {...}.
• Freeze fixtures so tests cannot change them by accident: Object.freeze(mockUser).
• Remove real personal data - names, emails, tokens - before committing a copied API response.
• For TypeScript, generate an interface too, so the fixture is type-checked.

Generate types with JSON to TypeScript. Need PHP or Python instead? See JSON to PHP Array and JSON to Python.