I have a build script that runs all my code through uglifyjs, does a bunch of fancy caching stuff, and ultimately runs eval( code ) on some JavaScript files.

I'm trying to get this whole process up and running with source maps, but I can't seem to get it working as long as I'm using eval. If I link to the files directly using <script src="..."> it works fine.

In my eval code, I have:

code, blah blah blah
//@ sourceMappingURL=/cache/618a67795c7460184bd9b99020cbb9fd.map

and then in that .map file, I have:

{
      "version"  : 3
    , "file"     : "618a67795c7460184bd9b99020cbb9fd.map"
    , "sources"  : ["/js/Parallax-JS/js/parallax-2.js"]
    , "names"    : [
          "a"
        , "bunch"
        , "of"
        , "variable"
        , "names"
    ]
    , "mappings" : "... LONG MAP ..."
}

I've tried putting //@ sourceURL= at the end instead, and that at least gives me the correct file name, but still no readable source.

Any ideas? Testing in Chrome 25 (dev) and 26 (canary)

I have a build script that runs all my code through uglifyjs, does a bunch of fancy caching stuff, and ultimately runs eval( code ) on some JavaScript files.

I'm trying to get this whole process up and running with source maps, but I can't seem to get it working as long as I'm using eval. If I link to the files directly using <script src="..."> it works fine.

In my eval code, I have:

code, blah blah blah
//@ sourceMappingURL=/cache/618a67795c7460184bd9b99020cbb9fd.map

and then in that .map file, I have:

{
      "version"  : 3
    , "file"     : "618a67795c7460184bd9b99020cbb9fd.map"
    , "sources"  : ["/js/Parallax-JS/js/parallax-2.js"]
    , "names"    : [
          "a"
        , "bunch"
        , "of"
        , "variable"
        , "names"
    ]
    , "mappings" : "... LONG MAP ..."
}

I've tried putting //@ sourceURL= at the end instead, and that at least gives me the correct file name, but still no readable source.

Any ideas? Testing in Chrome 25 (dev) and 26 (canary)

• javascript
• source-maps

• This seems to offer a solution: kybernetikos.github.io/jsSandbox/srcmaps/dynamic.html - but I want to state I did not personally try it. – Sebastian N. Commented May 8, 2023 at 13:40

2 Answers 2

I had a similar problem and the solution seem to be using an inlined SourceMaps (DataURL of a SourceMap).

Here is an example:

eval("blah blah\n//@ sourceMappingURL=data:application/json;base64,...");

Seems like you can't reference external resources from an eval.

I think you also need to use sourcesContent to insert the source code into the SourceMap.

Tested with Chrome 32.

Here is a setup using Grunt to pile javascript to single file using uglify with a source map

package.json

"src": {
    "js": "src/js"
},
"dest": {
    "js": "bin/js"
}

Gruntfile.js

grunt.initConfig({
    /**
     * Loading in the package file to read source and destination directories
     */
    pkg: grunt.file.readJSON('package.json'),
    uglify: {
    options: {
        banner: '/* all.min.js <%= grunt.template.today("dd-mm-yyyy") %> */\n',
        sourceMap: '<%= pkg.dest.js %>/all.min.js.map',
        sourceMappingURL: 'all.min.js.map',
        sourceMapRoot: '../../',
        mangle: false
        /*mangle: {
            except: ['jQuery']
        }*/
    },
    js: {
        src: [
            '<%= pkg.src.js %>/**/*.js'
        ],
        dest: '<%= pkg.dest.js %>/all.min.js'
    }
    }
};

grunt.loadNpmTasks('grunt-contrib-uglify');
grunt.registerTask('min', ['uglify']);

Which creates the following files:

all.min.js

/* all.min.js 04-10-2013 */
angular.module("App",[])
//# sourceMappingURL=all.min.js.map

all.min.js.map

{"version":3,"file":"bin/js/all.min.js","sources":["src/js/App.js"],"names":["angular","module"],"mappings":"AAeAA,QAAQC","sourceRoot":"../../"}