lesshint

lesshint

lesshint is a tool to aid you in writing clean and consistent Less.

• Requirements
• Installation
• Configuration
• CLI usage
• Reporters

Requirements

Node.js 0.10 (or later) or io.js 1.0 (or later).

Installation

Run the following command from the command line (add -g to install globally):

npm install lesshint

Configuration

lesshint is customizable and we highly recommend you to look at the available options to tailor it to your needs.

Start by creating a .lesshintrc file in your project root and add your settings to it. It will be automatically loaded and merged with the default values.

Each option is then specified by it's own JSON object, for example:

"fileExtensions": [".less", ".css"],

"excludedFiles": ["vendor.less"],

"spaceAfterPropertyColon": {
    "enabled": true,
    "style": "one_space" // Comments are allowed
}

Inline configuration

Since 1.4.0 it's possible to configure rules using inline comments in your .less files. For example:

// lesshint spaceBeforeBrace: false
.foo{ // This line won't be reported
    color: red;
}

It's also possible to disable rules on a single line using a trailing comment:

.bar {
    color:red; // lesshint spaceAfterPropertyColon: false
}

If you wish to enable a rule that's disabled in your .lesshintrc you need to specify any other options too. But rules without options can be enabled by just setting it to true. For example:

.lesshintrc:

{
    "emptyRule": false,
    "spaceAfterPropertyName": false
}

file.less

// lesshint spaceAfterPropertyName: { enabled: true, style: "one_space" }, emptyRule: true
.foo {
    color : red; // Won't report the extra space before ":"
}

.bar {

}

The options format is a less strict form of JSON. Keys doesn't need any quotes but string values need double quotes.

Options

fileExtensions

Array of file extensions to check. Either an array of extensions or "*" to allow all files. For example:

"fileExtensions": [".less", ".css"] // Allow ".less" and ".css" files. Can be passed with or without a dot.

"fileExtensions": "*" // Allow all files

excludedFiles

Array of minimatch glob patterns or a file to exclude. For example:

"excludedFiles": ["vendor/*.less"] // Ignore all files in "vendor/"

"excludedFiles": ["vendor.less"] // Ignore a file named "vendor.less"

CLI usage

Run lesshint from the command-line by passing one or more files/directories to recursively scan.

lesshint src/less/ lib/style.less

Available Flags	Description
-c/--config	Specify the configuration file to use (will be merged with defaults).
-e/--exclude	A minimatch glob pattern or a file to exclude form being linted.
-r/--reporter	The reporter to use. See "Reporters" below for possible values.
-V/--version	Show version.

Exit status codes

Depending on the linter results and options supplied, the exit status code returned by the CLI will differ.

Exit status code	Description
0	Everything is alright, no linting errors found.
1	One or more linting errors with a severity of warning was found.
2	One or more linting errors with a severity of error was found (since 1.3.0).
66	No files to lint were supplied.
70	An unknown error occurred within lesshint, possibly a bug. Please file an issue!
78	Something is wrong with the config file, most likely invalid JSON.

These codes were chosen with regards to the preferable exit codes.

Reporters

As of 0.8.0 the ability to specify custom reporters has been added. These can do anything from just printing something to the terminal to generate custom reports.

There are three ways to load a reporter.

1. Pass the name of a core reporter. See below for a complete listing.
2. Pass the name of a Node module. If lesshint is installed globally only globally installed reporters are available (the normal Node module loading rules apply).
3. Pass a absolute or relative path to a custom reporter anywhere on the disk. Relative paths will be resolved against process.cwd().

Core reporters

• stylish - Colored print of all errors to the console.

Writing your own reporter

In it's simplest form, a reporter is just a function accepting some input. The most basic reporter possible:

module.exports = {
    report: function (errors) {
        console.log(errors.length ? 'Errors found' : 'No errors');
    }
};

// Old usage, deprecated as of 1.2.0:
module.exports = function (errors) {
    console.log(errors.length ? 'Errors found' : 'No errors');
};

The reporter will be passed an array of objects representing each error:

{
    column: 5,
    file: 'file.less',
    fullPath: 'path/to/file.less',
    line: 1,
    linter: 'spaceBeforeBrace',
    message: 'Opening curly brace should be preceded by one space.',
    severity: 'warning',
    source: '.foo{'
}

It's then up to the reporter to do something with the errors. No returns or anything is needed. lesshint will handle everything like exit codes etc.

Take a look at the default reporter for more information.