postcss-reporter

What is postcss-reporter?

The postcss-reporter npm package is a PostCSS plugin used to log PostCSS messages in the console. It is designed to report warnings or messages from other PostCSS plugins in a clear and readable format. This helps developers understand and address issues during the CSS processing workflow.

What are postcss-reporter's main functionalities?

Logging Messages

This feature allows the logging of messages from other PostCSS plugins. The 'clearReportedMessages' option clears the messages after they are logged, preventing duplicate reporting.

postcss([ require('autoprefixer'), require('postcss-reporter')({ clearReportedMessages: true }) ]).process(css, { from: undefined }).then(result => { console.log(result.css); });

Custom Formatter

This feature allows developers to define a custom formatter function to format the output of the messages according to their needs.

postcss([ require('postcss-reporter')({ formatter: function(input) { return 'Total warnings: ' + input.messages.length; } }) ]).process(css, { from: undefined }).then(result => { console.log(result.css); });

Other packages similar to postcss-reporter

postcss-log-warnings

This package is similar to postcss-reporter as it also focuses on logging warnings from PostCSS plugins. However, it is more specific to warnings and does not provide as much flexibility in terms of custom formatting or handling different types of messages.

stylelint

While primarily a CSS linter, stylelint can be used in conjunction with PostCSS to report issues in CSS files. It offers a broader range of rules and configurations compared to postcss-reporter, which is focused only on reporting and formatting messages from other plugins.

README

postcss-reporter

A PostCSS plugin to console.log() the messages (warnings, etc.) registered by other PostCSS plugins.

Purpose

As of PostCSS 4.1, a single PostCSS process can accumulate messages from all of the plugins it uses. Most of these messages are warnings. Presumably, plugin authors want you to see those messages. So this plugin exists to read the accumulated messages (or messages from only the plugins you've specified), format them, and print them to the console.

By default, the messages are formatted for human legibility and sorted according to the line/column positions attached to the messages. But another formatting function can be passed in with an option, and sorting can be turned of with an option.

By default, only warnings are logged. If you would like to see more messages, you can change the filter function.

Example Output

Installation

npm install postcss-reporter

Version 1.0.0+ is compatible with PostCSS 5+. (Earlier versions are compatible with PostCSS 4.)

Usage

Add it to your plugin list after any plugins whose messages you want to log, and optionally pass it an object of options.

For example, using gulp-postcss:

gulp.task('css', function() {
  return gulp.src('./src/*.css')
    .pipe(postcss([
      bemLinter(),
      customProperties(),
      calc(),
      rejectAllColors(),
      reporter(myOptions) // <------ ding
    ]))
    .pipe(gulp.dest('./dist'));
});

Options

clearMessages (boolean, default = false)

If true, the plugin will clear the result's messages after it logs them. This prevents other plugins, or the whatever runner you use, from logging the same information again and causing confusion.

formatter (function, default = the default formatter)

By default, this reporter will format the messages for human legibility in the console. To use another formatter, pass a function that

• accepts an object containing a messages array and a source string
• returns the string to report

For example, you could write a formatter like this:

reporter({
  formatter: function(input) {
    return input.source + ' produced ' + input.messages.length + ' messages';
  }
})

plugins (array of strings, default = [])

If plugins is empty (as it is by default), the reporter will log messages from every PostCSS plugin.

There are 2 ways to limit output:

• Whitelist: Provide an array of the plugins whose messages you would like to show. For example, { plugins: ['postcss-bem-linter'] } will only log messages from the postcss-bem-linter plugin.
• Blacklist: Prefix all plugins in the array with ! to specify only those plugins whose messages you would like to hide. (All other plugins will be shown.) For example, { plugins: ['!postcss-bem-linter'] } will never log messages from the postcss-bem-linter plugin; but will log messages from every other plugin.

filter (function)

Provide a filter function. It receives the message object and returns a truthy or falsy value, indicating whether that particular message should be reported or not.

By default, only messages with type: "warning" warnings are logged. (These are the messages produced when the plugin author uses PostCSS's warn() function.)

For example, function(message) { return true } will only every message, regardless of the plugin or whether it's a warning or not.

throwError (boolean, default = false)

If true, after the plugin logs your messages it will throw an error if it found any warnings.

sortByPosition (boolean, default = true)

If false, messages will not be sorted by line/column position.

positionless ("first"|"last"|"any", default = "first")

By default, messages without line/column positions will be grouped at the beginning of the output. To put them at the end, instead, use "last". To not bother sorting these, use "any".

noIcon (boolean, default = false)

If true, no exclamatory triangle icons will be printed next to warnings.

noPlugin (boolean, default = false)

If true, plugin names will not be printed in brackets after messages.

How to get output without colors

If you would like no colors in the console output, simply pass --no-colors when you invoke whatever command runs this plugin. (This works because of chalk.)

Standalone formatter

You can also use this module's formatter as a library, with following API:

var formatter = require('postcss-reporter/lib/formatter');
var myFormatter = formatter(myOptions);
// to use defaults, just pass no options: `formatter()`
var warningLog = myFormatter({
  messages: someMessages,
  source: someSource
});
console.log(warningLog);

These are the formatter's options:

• sortByPosition (boolean, default = true)
• noIcon (boolean, default = false) - Do not print any warning exclamatory triangle icons
• noPlugin (boolean, default = false) - Do not print plugin names

Changelog

2.0.0

• Only log warning messages (type: "warning") by default.