gulp-sourcemaps

Source map support for Gulp.js

gulp-sourcemaps

Usage

Write inline source maps

Inline source maps are embedded in the source file.

Example:

var gulp = require('gulp');
var plugin1 = require('gulp-plugin1');
var plugin2 = require('gulp-plugin2');
var sourcemaps = require('gulp-sourcemaps');
 
gulp.task('javascript', function() {
  gulp.src('src/**/*.js')
    .pipe(sourcemaps.init())
      .pipe(plugin1())
      .pipe(plugin2())
    .pipe(sourcemaps.write())
    .pipe(gulp.dest('dist'));
});

All plugins between sourcemaps.init() and sourcemaps.write() need to have support for gulp-sourcemaps. You can find a list of such plugins in the wiki.

Write external source map files

To write external source map files, pass a path relative to the destination to sourcemaps.write().

Example:

var gulp = require('gulp');
var plugin1 = require('gulp-plugin1');
var plugin2 = require('gulp-plugin2');
var sourcemaps = require('gulp-sourcemaps');
 
gulp.task('javascript', function() {
  gulp.src('src/**/*.js')
    .pipe(sourcemaps.init())
      .pipe(plugin1())
      .pipe(plugin2())
    .pipe(sourcemaps.write('../maps'))
    .pipe(gulp.dest('dist'));
});

Load existing source maps

To load existing source maps, pass the option loadMaps: true to sourcemaps.init().

Example:

var gulp = require('gulp');
var plugin1 = require('gulp-plugin1');
var plugin2 = require('gulp-plugin2');
var sourcemaps = require('gulp-sourcemaps');
 
gulp.task('javascript', function() {
  gulp.src('src/**/*.js')
    .pipe(sourcemaps.init({loadMaps: true}))
      .pipe(plugin1())
      .pipe(plugin2())
    .pipe(sourcemaps.write())
    .pipe(gulp.dest('dist'));
});

Handle source files from different directories

Use the base option on gulp.src to make sure all files are relative to a common base directory.

Example:

var gulp = require('gulp');
var plugin1 = require('gulp-plugin1');
var plugin2 = require('gulp-plugin2');
var sourcemaps = require('gulp-sourcemaps');
 
gulp.task('javascript', function() {
gulp.src(['src/test.js', 'src/testdir/test2.js'], { base: 'src' })
    .pipe(sourcemaps.init())
      .pipe(plugin1())
      .pipe(plugin2())
    .pipe(sourcemaps.write('../maps'))
    .pipe(gulp.dest('dist'));
});

Init Options

• loadMaps Set to true to load existing maps for source files. Supports the following:

  • inline source maps
  • source map files referenced by a sourceMappingURL= comment
  • source map files with the same name (plus .map) in the same directory

• debug Set this to true to output debug messages (e.g. about missing source content).

Write Options

• addComment

  By default a comment containing / referencing the source map is added. Set this to false to disable the comment (e.g. if you want to load the source maps by header).

  Example:

  gulp.task('javascript', function() {
    var stream = gulp.src('src/**/*.js')
      .pipe(sourcemaps.init())
        .pipe(plugin1())
        .pipe(plugin2())
      .pipe(sourcemaps.write('../maps', {addComment: false}))
      .pipe(gulp.dest('dist'));
  });

• includeContent

  By default the source maps include the source code. Pass false to use the original files.

  Including the content is the recommended way, because it "just works". When setting this to false you have to host the source files and set the correct sourceRoot.

• sourceRoot

  Set the path where the source files are hosted (use this when includeContent is set to false). This is an URL (or subpath) relative to the source map, not a local file system path. If you have sources in different subpaths, an absolute path (from the domain root) pointing to the source file root is recommended, or define it with a function.

  Example:

  gulp.task('javascript', function() {
    var stream = gulp.src('src/**/*.js')
      .pipe(sourcemaps.init())
        .pipe(plugin1())
        .pipe(plugin2())
      .pipe(sourcemaps.write({includeContent: false, sourceRoot: '/src'}))
      .pipe(gulp.dest('dist'));
  });

  Example (using a function):

  gulp.task('javascript', function() {
    var stream = gulp.src('src/**/*.js')
      .pipe(sourcemaps.init())
        .pipe(plugin1())
        .pipe(plugin2())
      .pipe(sourcemaps.write({
        includeContent: false,
        sourceRoot: function(file) {
          return '/src';
        }
       }))
      .pipe(gulp.dest('dist'));
  });

• sourceMappingURLPrefix

  Specify a prefix to be prepended onto the source map URL when writing external source maps. Relative paths will have their leading dots stripped.

  Example:

  gulp.task('javascript', function() {
    var stream = gulp.src('src/**/*.js')
      .pipe(sourcemaps.init())
        .pipe(plugin1())
        .pipe(plugin2())
      .pipe(sourcemaps.write('../maps', {
        sourceMappingURLPrefix: 'https://asset-host.example.com/assets'
      }))
      .pipe(gulp.dest('public/scripts'));
  });

  Example (using a function):

  gulp.task('javascript', function() {
    var stream = gulp.src('src/**/*.js')
      .pipe(sourcemaps.init())
        .pipe(plugin1())
        .pipe(plugin2())
      .pipe(sourcemaps.write('../maps', {
        sourceMappingURLPrefix: function(file) {
          return 'https://asset-host.example.com/assets'
        }
      }))
      .pipe(gulp.dest('public/scripts'));
  });

  This will result in source mapping URL comment like sourceMappingURL=https://asset-host.example.com/assets/maps/helloworld.js.map.

• debug

  Set this to true to output debug messages (e.g. about missing source content).

Plugin developers only: How to add source map support to plugins

• Generate a source map for the transformation the plugin is applying
• Important: Make sure the paths in the generated source map (file and sources) are relative to file.base (e.g. use file.relative).
• Apply this source map to the vinyl file. E.g. by using vinyl-sourcemaps-apply. This combines the source map of this plugin with the source maps coming from plugins further up the chain.
• Add your plugin to the wiki page

Example:

var through = require('through2');
var applySourceMap = require('vinyl-sourcemaps-apply');
var myTransform = require('myTransform');
 
module.exports = function(options) {
 
  function transform(file, encoding, callback) {
    // generate source maps if plugin source-map present 
    if (file.sourceMap) {
      options.makeSourceMaps = true;
    }
 
    // do normal plugin logic 
    var result = myTransform(file.contents, options);
    file.contents = new Buffer(result.code);
 
    // apply source map to the chain 
    if (file.sourceMap) {
      applySourceMap(file, result.map);
    }
 
    this.push(file);
    callback();
  }
 
  return through.obj(transform);
};