source-map-resolve

Resolve the source map and/or sources for a generated file.

Overview

Resolve the source map and/or sources for a generated file.

var sourceMapResolve = require("source-map-resolve")
var sourceMap        = require("source-map")
 
var code = [
  "!function(){...}();",
  "/*# sourceMappingURL=foo.js.map */"
].join("\n")
 
sourceMapResolve.resolveSourceMap(code, "/js/foo.js", fs.readFile, function(errorresult) {
  if (error) {
    return notifyFailure(error)
  }
  result
  // { 
  //   map: {file: "foo.js", mappings: "...", sources: ["/coffee/foo.coffee"], names: []}, 
  //   url: "/js/foo.js.map", 
  //   sourcesRelativeTo: "/js/foo.js.map", 
  //   sourceMappingURL: "foo.js.map" 
  // } 
 
  sourceMapResolve.resolveSources(result.map, result.sourcesRelativeTo, fs.readFile, function(errorresult) {
    if (error) {
      return notifyFailure(error)
    }
    result
    // { 
    //   sourcesResolved: ["/coffee/foo.coffee"], 
    //   sourcesContent: ["<contents of /coffee/foo.coffee>"] 
    // } 
  })
})
 
sourceMapResolve.resolve(code, "/js/foo.js", fs.readFile, function(errorresult) {
  if (error) {
    return notifyFailure(error)
  }
  result
  // { 
  //   map: {file: "foo.js", mappings: "...", sources: ["/coffee/foo.coffee"], names: []}, 
  //   url: "/js/foo.js.map", 
  //   sourcesRelativeTo: "/js/foo.js.map", 
  //   sourceMappingURL: "foo.js.map", 
  //   sourcesResolved: ["/coffee/foo.coffee"], 
  //   sourcesContent: ["<contents of /coffee/foo.coffee>"] 
  // } 
  result.map.sourcesContent = result.sourcesContent
  var map = new sourceMap.sourceMapConsumer(result.map)
  map.sourceContentFor("/coffee/foo.coffee")
  // "<contents of /coffee/foo.coffee>" 
})

Installation

  • npm install source-map-resolve
  • bower install source-map-resolve
  • component install lydell/source-map-resolve

Works with CommonJS, AMD and browser globals, through UMD.

Note: This module requires setImmediate and atob. Use polyfills if needed, such as:

Usage

  • code is a string of code that may or may not contain a sourceMappingURL comment. Such a comment is used to resolve the source map.
  • codeUrl is the url to the file containing code. If the sourceMappingURL is relative, it is resolved against codeUrl.
  • read(url, callback) is a function that reads url and responds using callback(error, content). In Node.js you might want to use fs.readFile, while in the browser you might want to use an asynchronus XMLHttpRequest.
  • callback(error, result) is a function that is invoked with either an error or null and the result.

The result is an object with the following properties:

  • map: The source map for code, as an object (not a string).
  • url: The url to the source map. If the source map came from a data uri, this property is null, since then there is no url to it.
  • sourcesRelativeTo: The url that the sources of the source map are relative to. Since the sources are relative to the source map, and the url to the source map is provided as the url property, this property might seem superfluos. However, remember that the url property can be null if the source map came from a data uri. If so, the sources are relative to the file containing the data uri—codeUrl. This property will be identical to the url property or codeUrl, whichever is appropriate. This way you can conveniently resolve the sources without having to think about where the source map came from.
  • sourceMappingURL: The url of the sourceMappingURL comment in code.

If code contains no sourceMappingURL, the result is null.

  • map is a source map, as an object (not a string).
  • mapUrl is the url to the file containing map. Relative sources in the source map, if any, are resolved against mapUrl.
  • read(url, callback) is a function that reads url and responds using callback(error, content). In Node.js you might want to use fs.readFile, while in the browser you might want to use an asynchronus XMLHttpRequest.
  • options is an optional object with any of the following properties:
    • ignoreSourceRoot: The sourceRoot property of source maps might only be relevant when resolving sources in the browser. This lets you bypass it when using the module outside of a browser, if needed. Defaults to false.
  • callback(error, result) is a function that is invoked with either an error or null and the result.

The result is an object with the following properties:

  • sourcesResolved: The same as map.sources, except all the sources are fully resolved.
  • sourcesContent: An array with the contents of all sources in map.sources, in the same order as map.sources.

The arguments are identical to sourceMapResolve.resolveSourceMap, except that you may also provide the same options as in sourceMapResolve.resolveSources.

This is simply a convienience method that first resolves the source map and then its sources. You could also do this by first calling sourceMapResolve.resolveSourceMap and then sourceMapResolve.resolveSources.

The result is identical to sourceMapResolve.resolveSourceMap, with the properties from sourceMapResolve.resolveSources merged into it.

There are also sync versions of the three previous functions. They are identical to the async versions, except:

  • They expect a sync reading function. In Node.js you might want to use fs.readFileSync, while in the browser you might want to use a synchronus XMLHttpRequest.
  • They throw errors and return the result instead of using a callback.

sourceMapResolve.resolveSourcesSync also accepts null as the read parameter. The result is the same as when passing a function as the read parameter, except that the sourcesContent property of the result will be an empty array. In other words, the sources aren’t read. You only get the sourcesResolved property. (This only supported in the synchronus version, since there is no point doing it asynchronusly.)

Note

This module resolves the source map for a given generated file by looking for a sourceMappingURL comment. The spec defines yet a way to provide the URL to the source map: By sending the SourceMap: <url> header along with the generated file. Since this module doesn’t retrive the generated code for you (instead you give the generated code to the module), it’s up to you to look for such a header when you retrieve the file (should the need arise).

Development

First off, run npm install to install testing modules and browser polyfills.

npm test lints the code and runs the test suite in Node.js.

To run the tests in a browser, run testling (npm install -g testling) or testling -u.

package.json, component.json and bower.json are all generated from x-package.json5 by using xpkg. Only edit x-package.json5, and remember to run xpkg before commiting!

source-map-resolve.js is generated from source-map-resolve-node.js and source-map-resolve-template.js. Only edit the two latter files, not source-map-resolve.js! To generate it, run npm run build.

License

The X11 (“MIT”) License.