Using custom linters via the CLI

The README indicates custom linters can be defined via the CLI via the --linters option, however, from my experience adding custom linters to the lesshintrc file they must also be enabled. Can you provide an example of custom linter usage via the CLI as it is unclear how to both define and enable the customer linter via the CLI.

Thanks.

[JoshuaKGoldberg]

Hi, yes! It “should”* be a relatively simple process. Something like following should probably end up in the docs in some form…

First, create a JavaScript file somewhere that looks like one of the linters from lesshint’s lib/linters directory. important_rule.js is a pretty simple starting point.

As a custom example, here’s a rule that logs on every declaration:

// verbose_rule.js
'use strict';

console.log('Loaded verbose_rule.js.');

module.exports = {
    name: 'verbose',
    nodeTypes: ['decl'],

    lint: function verboseLinter(config, node) {
        console.log('Found node setting', node.prop, 'to', node.value);
    }
};

Given the following file named test.less…

.foo {
    color: bar;
}

…and a .lesshintrc file that enables the rule…

{
    "verbose": true
}

…if you run the following command* (assuming you’ve run npm i -g lesshint)…

lesshint test.less --linters C:/Code/lesshint-testing/verbose_rule.js

…you should get the following output:

Loaded verbose_rule.js.
Found node setting color to bar

You can then extend the linter to return an array of failures.

*After testing v2.4.0 today, it looks like the require logic requires relative to the lesshint install, not the script calling it. I’ll fix that ASAP. You can get around it by using the absolute paths (C:/Code/my-lesshint-stuff/linter.js instead of ./linter.js). As per this SO answer you can debug where Node is looking for objects via require. export NODE_DEBUG=module on *nix; set NODE_DEBUG=module on Windows.

[jwilsson]

Closing this since it’s better documented now.

@kloots Please give us a shout if you disagree!