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grunt-banner

Adds a simple banner to files

grunt-banner

Adds a simple banner to files

This plugin requires Grunt >=0.4.0

If you haven't used Grunt before, be sure to check out the Getting Started guide, as it explains how to create a Gruntfile as well as install and use Grunt plugins. Once you're familiar with that process, you may install this plugin with this command:

npm install grunt-banner --save-dev

Once the plugin has been installed, it may be enabled inside your Gruntfile with this line of JavaScript:

grunt.loadNpmTasks('grunt-banner');

Or if you are using matchdep it will be included along with other grunt-* tasks by using this line of JavaScript:

require('matchdep').filterDev('grunt-*').forEach(grunt.loadNpmTasks);

grunt-banner renamed its task from banner to usebanner as a banner is often used to hold a banner template for a number of grunt plugins.

In your project's Gruntfile, add a section named usebanner to the data object passed into grunt.initConfig().

The wildcard selector * is perfectly valid for selecting targets to add a banner to.

grunt.initConfig({
  usebanner: {
    taskName: {
      options: {
        position: 'top',
        banner: '// banner text <%= templates encouraged %>',
        linebreak: true
      },
      files: {
        src: [ 'path/to/file.ext', 'path/to/another/*.ext' ]
      }
    }
  }
})

Type: String
Default: 'top'
Value range: 'top' or 'bottom' or 'replace'

The position to place the banner - either the top or bottom or in place of the contents in the desired file specified by 'replaceContent' when and existing banner is replaced by grunt-banner.

When position is set to 'replace', this implies options.replace: true unless that option has explicitly been set by the user already (see below).

When position is set to 'replace' and replacement fails, i.e. no existing banner could be spotted, then grunt-banner falls back to regular position: 'top' | position: 'bottom' banner insertion behaviour.

In short: grunt-banner will always either replace or add a banner!

Type: Boolean, String, RegExp or Function

The text in the specified file that the banner should replace. When position is set to 'replace', every occurrence of a banner (see below for more on how existing banners are located) will be replaced by the new one. When position is set to either 'top' or 'bottom', then the existing banners will be removed and replaced by a single new banner at the top or bottom of the file as directed by the position setting.

These options.replace parameter types / values are supported:

  • Boolean false (default) - do not look for existing banners; simply add the banner at the specified position (top / bottom).

  • Boolean true - 'smart' replace mode: use the built-in 'smart' locate-and-mark scanner to dig out the existing banners (more on the rules what maketh a banner below).

  • (string) - replace any part of the source code which matches this implicit regex.

    This means most strings are matched as-is, but do not get mistaken about this: dot ., star * et al will not be the literal characters you might have expected, but are treated as regex operators! E.g. replace: "/* blurb */" will not work as if a literal string, since the stars * in there will make it match lines like // blurb // but will not match an actual C-style comment line /* blurb */. You will need to specify the proper regex string for that instead: replace: "\/\* blurb \*\/".

    Also note that every regex match will be replaced by the specified banner. If your regex is not selective or precise enough, you may end up with some surprising replacements. This is not a bug. You are responsible for providing fitting regexes to have grunt-banner match against.

  • (RegExp) - a rexexp instance to match against. The same caveats as the (string) type value above apply.

  • (function) - provide your own callback method to locate and mark the input. The interface for the callback function is:

    function (fileContents, newBanner, insertPositionMarker, src, options)

    which should return the marked fileContents, i.e. the fileContents with all banners eligible for replacement removed and replaced by a simple insertPositionMarker string (see below). Your locate-and-match callback may insert one, multiple markers or none: grunt-banner will check how many markers you injected and either replace them when one or more markers are seen, or when none are found, revert to its basic top|bottom position-based banner insertion process.

    The callback function parameters:

    • fileContents (string) - the contents of the src file.

    • newBanner (string) - the new banner to be inserted by grunt-banner.

      This (and the options parameter, see below) allows you to customize grunt-banner behaviour to an extreme degree, even providing your own custom replacer entirely: simply return your processed result with a single marker and reduce the options.banner to an empty string. But I digress...

    • insertPositionMarker (string) - the insert marker.

      Currently this is the Unicode REPLACEMENT CHARACTER character, i.e. \uFFFD. We assume your original file content does not contain this marker already.

    • src (string) - the path to the file being processed.

    • options (object reference) - a reference to the current options object as used by grunt-banner.

      This is not the same as the options object you provided through your Gruntfile; this is a reference to the updated/augmented clone of that original as used by grunt-banner internally.

      Though the following coding practice should be frowned upon as 'side effects' are generally undesirable, you can tweak the options.banner value to suit your custom needs, for example.

      Tread with great care when you are about to edit attributes in this options object reference! The fact that you can doesn't mean you should fiddle with it!

Type: String

The text to use as a banner. Templated strings are perfectly acceptable and encouraged.

Type: String

Allows the banner to be added only if the supplied pattern matches.

Type: Boolean
Default: true

Set linebreak to true to add a line break between banner and file content.

Type: Function

Allows the banner to be generated for each file using the output of the process function.

The default locate-and-mark process, invoked when you specify the replace: true option (or position: "replace" without any replace: value to go with that one) is set up to locate copyright banner comment chunks in either C or C++ style format, i.e. surrounded by /*....*/ or single- or multiline // comment chunks.

The process will inspect each comment chunk which start at the left edge (hence we ignore all indented comment chunks!) and which span entire lines, hence ruling out any comments which are leading or trailing source code statements on the same line.

The last restriction placed on any 'old' banner to replace is that it must have the (case-insensitive) word Copyright in there somewhere. And that word must be followed by a bit of non-whitespace blurb on the same line: generally a year, a name or both suffices to satisfy this last condition.

Any such 'banner' block is marked for replacement in its entirety.

The replacer does not check if the new banner also includes the Copyright phrase, hence multiple applications of grunt-banner may lead to the later rounds of grunt-banner application adding the shiny new banner at the top (or bottom) of the source file.

In this example an appConfig is read from a JSON file and used to populate a banner template which is then used by grunt-banner to place at the top of some files. Each file in the array will have the banner placed on to it and all .js files in the /more-scripts/ folder will have a banner thanks to the * wildcard.

var appConfig = grunt.file.readJSON( 'app-config.json' ) || {};
grunt.initConfig({
  banner: '/* <%= appConfig.info.name %> - version <%= appConfig.info.version %> - ' +
          '<%= grunt.template.today("dd-mm-yyyy") %>\n' +
          '<%= appConfig.info.description %>\n ' +
          '&#169 <%= grunt.template.today("yyyy") %> <%= appConfig.info.author.name %> ' +
          '- <%= appConfig.info.author.email %> */\n',
  usebanner: {
    dist: {
      options: {
        position: 'top',
        banner: '<%= banner %>'
      },
      files: {
        src: [ 'scripts/main-min.js', 'stylesheets/main-min.css', 'more-scripts/*.js' ]
      }
    }
  }
})

By supplying a process function you effectively take control of how the banner is generated, the task is still responsible for placing it. In essence, it replaces the need for a banner object being specified in your grunt config as you are creating it from code for each file. This gives you the flexibility to add file-specific data to your banners.

This example uses grunt templating to generate a banner that references the file name it is being appended to. Run the test cases to see this in action.

usebanner: {
  dist: {
    options: {
      position: 'top',
      process: function ( filepath ) {
        return grunt.template.process(
          '// banner for file: <%= filename %>', {
            data: {
              filename: filepath.match(/\/([^/]*)$/)[1]
            }
          }
        );
      }
    },
    files: {
      src: [ 'test/tmp/someProcess.js' ]
    }
  }
}

grunt-banner adds the banner to the head or foot of the files that are specified by the array passed to files.src unless ways to see if a banner already exists have been properly set up (options.replace and/or position: 'replace').

It is up to the user to ensure that either the file should not already contain a banner or that the configured locate-and-mark means (default locate-and-mark function, user-specified regex or user-specified callback function) are sufficient to ensure that no undesired code chunk replacements may occur. To this end it is recommended to use the grunt-contrib-clean task and only add banners to built code.

In lieu of a formal style guide, take care to maintain the existing coding style. Add unit tests for any new or changed functionality. Lint and test your code using Grunt.