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Static analysis tool for detecting browser compatibility issues in JavaScript and HTML.
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compat.js Build Status

Static analysis tool for detecting browser compatibility issues in JavaScript and HTML.


npm install compat-cli


By default, compat will check files ending with .js or .html in the current directory.


To manually specify target files/directories, use the --target (-t) flag.

compat --target fileOne.js fileTwo.js directory

By default, compat will not recursively traverse directories to find all .js or .html files. Enable this functionality with the --recursive (-r) flag.

compat --recursive

By default, compat will search for all defined features when analysing targets. To specify what features compat will search for, use the --features (-f) flag.

compat --features es6-bindings let

The features flag supports both specifying individual features (like let in the above example) or specifying feature groups (like es6-bindings). Use the --supportedFeatures and --supportedFeatureGroups flags to show available features and feature groups.

Additionally, individual features or feature groups can be ignored using the --ignoreFeatures (-i) flag. The below example will detect all defined ES6 features, except for those relating to syntax.

compat --features es6 --ignoreFeatures es6-syntax

When run with the --enabledFeatures flag, compat will print out a list of features that it will be enabled for detection with the provided flags.

By default, compat will check for compatibility issues with the following environments:

  • Internet Explorer 11
  • Microsoft Edge 13 & 14
  • Chrome 56
  • Safari 9 & 10
  • Firefox 51

Use the --jsEnvs (-j) and --htmlEnvs (-h) flags to specify which environments to check for issues. Use the ---supportedEnvs flag to show available environments. There are separate flags for JS and HTML environments because they use different sources for their compatibility info.

compat --jsEnvs ie11 chrome54 --htmlEnvs ie11

All of the above flags can be specified in a config file. By default, compat will try to read ./.compatrc.json, but another config file can be specified with the --config (-c) flag. The config file must end with .json.

compat --config ./configs/compat-config.json

When run, compat will try to update its locally stored compatibility table if the sources for compatibility info have changed. Info for JS compatibility is loaded from kangax's compat-table and info for HTML compatibility is loaded from fyrd's caniuse. If the updated tables cannot be loaded for some reason, compat will use the last table it downloaded for checking compatibility.


Run tests with:

npm test

Lint with:

npm run lint



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