Check JavaScript code compatibility with target browsers and Node.js versions
Checks that the language features used in your code/bundles are supported by your browserslist targets.
- check-es-compat - standalone CLI tool
- eslint-plugin-ecmascript-compat - ESLint plugin
You might not need a transpiler or polyfills.
Or, you may be transpiling your own code but not prebuilt 3rd-party libraries - leaving you open to breakages when they use new language features.
ESLint supports targeting a specific ECMAScript version, and eslint-plugin-es allows forbidding individual language features. However when building applications, what we target are particular browser/runtime versions. This project lets you check compatibility by specifying those targets directly via a browserslist. It will figure out which individual features you can use, by looking up those targets in the MDN compatibility dataset.
ECMAScript language features only; this includes syntax, built-ins, and methods.
It doesn't check browser/runtime-specific APIs (see eslint-plugin-compat), or CSS (see doiuse).
n Expand for footnotes...
1 Excluding features not statically detectable: revised Function.prototype.toString, stable Array.prototype.sort, well-formed JSON.stringify.
2 Excluding Symbol.prototype.description; as a debug feature, it's not worth the false positives that arise due to its name and not being a method.
3 ES2015 (ES6) is out of scope; it's been supported by evergreen browsers for many years. Assisting you to continue supporting IE11 is not a goal of this tool.
4 ES5 is out of scope; it's over 10 years old and supported even in IE10.
Because JavaScript is untyped, detection of some features' usage (namely prototype methods) through static analysis requires some assumptions to be made. This shouldn't be a problem as long as you avoid creating your own methods having the same names, or write code in an unusual way to deliberately evade detection.
The MDN compatibility dataset has very good coverage of the top ~6 desktop and mobile browsers, and Node.js (much more than kangax/compat-table). In case of missing data (support unknown, or unknown in which version support was added), we currently assume support.
Contributions and feedback welcome. Please see the GitHub issues or create one, as appropriate.
- eslint-plugin-compat - for browser APIs
- doiuse - for CSS
- eslint-plugin-es*
- @mdn/browser-compat-data*
* Thanks to these projects in particular (and many others) for making this project possible.