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Writing formatters

A formatter is a function with the following signature:

/** * @type {import('stylelint').Formatter} */function formatter(results, returnValue) {  return "a string of formatted results";}

Where the first argument (results) is an array of stylelint result objects (type Array<StylelintResult>) in the form:

// A stylelint result object{  "source": "path/to/file.css", // The filepath or PostCSS identifier like <input css 1>  "errored": true, // This is `true` if at least one rule with an "error"-level severity triggered a warning  "warnings": [    // Array of rule violation warning objects, each like the following ...    {      "line": 3,      "column": 12,      "rule": "block-no-empty",      "severity": "error",      "text": "You should not have an empty block (block-no-empty)"    }  ],  "deprecations": [    // Array of deprecation warning objects, each like the following ...    {      "text": "Feature X has been deprecated and will be removed in the next major version.",      "reference": ""    }  ],  "invalidOptionWarnings": [    // Array of invalid option warning objects, each like the following ...    {      "text": "Invalid option X for rule Y"    }  ],  "ignored": false // This is `true` if the file's path matches a provided ignore pattern}

And the second argument (returnValue) is an object (type StylelintStandaloneReturnValue) with one or more of the following keys:

{  "errored": false, // `true` if there were any warnings with "error" severity  "maxWarningsExceeded": {    // Present if stylelint was configured with a `maxWarnings` count    "maxWarnings": 10,    "foundWarnings": 15  }}

Passing arguments#

You can use environmental variables in your formatter. For example, pass SKIP_WARNINGS:

SKIP_WARNINGS=true stylelint "*.css" --custom-formatter ./my-formatter.js

Alternatively, you can create a separate formatting program and pipe the output from the built-in JSON formatter into it:

stylelint -f json "*.css" | my-program-that-reads-JSON --option


stylelint's internal formatters are exposed publicly in stylelint.formatters.