JSON to JavaScript Converter
Produce JavaScript classes or JSDoc typedefs from JSON, so a plain JS project still gets autocompletion and type checking.
Your data stays on your device
Input — JSON
- characters
- 0
- lines
- 0
- size
- 0 B
Output — JavaScript
- characters
- 0
- lines
- 0
- size
- 0 B
Options
About this tool
JavaScript has no type annotations, but editors understand JSDoc. A generated typedef block gives you the same autocompletion and inline errors that TypeScript users get, without changing your build or adding a compile step.
The class output is the alternative: a constructor that assigns each field, giving you a real runtime shape to instantiate. Both are produced from the same recursive analysis, so nested objects get their own typedef or class.
How to use this tool
- Paste your JSON sample.
- Choose JSDoc typedefs or ES class output.
- Set the root name and pick a naming convention for fields.
- Press Generate and copy the code into your project.
Key features
- JSDoc typedef blocks or ES6 class output
- Nested objects generated as their own typedef or class
- Constructor assignment for every field in class mode
- Optional fields marked with the JSDoc bracket syntax
- Reserved words and invalid identifiers handled safely
- Optional doc comments describing each field type
Example
Input — JSON
{"title":"Post","views":1200,"draft":false}Output — JavaScript
/**
* @typedef {Object} Root
* @property {string} title
* @property {number} views
* @property {boolean} draft
*/Good to know
- JSDoc types are not enforced at runtime. They are hints for your editor and for type-aware tooling only.
- Class output builds plain objects; it does not generate validation, serialisation or deep-clone logic.
- As with all sample-based inference, fields that are null in the input cannot be typed precisely.
Frequently asked questions
Why use JSDoc instead of TypeScript?
It requires no build step and no file extension changes. Editors and the TypeScript compiler in checkJs mode both read it, so an existing JavaScript codebase gets most of the benefit with none of the migration.
Do the generated classes validate input?
No. The constructor assigns whatever it is given. Add validation separately if the data comes from an untrusted source.
How are nested objects handled in class mode?
Each nested object becomes its own class, and the parent constructor is annotated to reference it.
Can I use the output with the TypeScript compiler?
Yes. With allowJs and checkJs enabled, tsc reads the JSDoc annotations and type-checks the file.
Your data stays on your device
Your data is processed locally in your browser and is not uploaded to our server. This page keeps working after you go offline, because there is nothing to send.