gulp-sourcemaps

Usage

Inline maps

Inline maps are embedded in the source file.

Example:

var gulp = require('gulp');
var concat = require('gulp-concat');
var uglify = require('gulp-uglify');
var sourcemaps = require('gulp-sourcemaps');

gulp.task('javascript', function() {
  gulp.src('src/**/*.js')
    .pipe(sourcemaps.init())
      .pipe(concat('all.js'))
      .pipe(uglify())
    .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.

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 concat = require('gulp-concat');
var uglify = require('gulp-uglify');
var sourcemaps = require('gulp-sourcemaps');

gulp.task('javascript', function() {
  gulp.src('src/**/*.js')
    .pipe(sourcemaps.init())
      .pipe(concat('all.js'))
      .pipe(uglify())
    .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 concat = require('gulp-concat');
var uglify = require('gulp-uglify');
var sourcemaps = require('gulp-sourcemaps');

gulp.task('javascript', function() {
  gulp.src('src/**/*.js')
    .pipe(sourcemaps.init({loadMaps: true}))
      .pipe(concat('all.js'))
      .pipe(uglify())
    .pipe(sourcemaps.write())
    .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

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(concat('all.js'))
        .pipe(uglify())
      .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(concat('all.js'))
        .pipe(uglify())
      .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(concat('all.js'))
        .pipe(uglify())
      .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(concat('all.js'))
        .pipe(uglify())
      .pipe(sourcemaps.write('../maps', {
        sourceMappingURLPrefix: '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.

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);
};