1Overview [![Build Status](https://travis-ci.org/lydell/source-map-resolve.svg?branch=master)](https://travis-ci.org/lydell/source-map-resolve)
2========
3
4Resolve the source map and/or sources for a generated file.
5
6```js
7var sourceMapResolve = require("source-map-resolve")
8var sourceMap        = require("source-map")
9
10var code = [
11  "!function(){...}();",
12  "/*# sourceMappingURL=foo.js.map */"
13].join("\n")
14
15sourceMapResolve.resolveSourceMap(code, "/js/foo.js", fs.readFile, function(error, result) {
16  if (error) {
17    return notifyFailure(error)
18  }
19  result
20  // {
21  //   map: {file: "foo.js", mappings: "...", sources: ["/coffee/foo.coffee"], names: []},
22  //   url: "/js/foo.js.map",
23  //   sourcesRelativeTo: "/js/foo.js.map",
24  //   sourceMappingURL: "foo.js.map"
25  // }
26
27  sourceMapResolve.resolveSources(result.map, result.sourcesRelativeTo, fs.readFile, function(error, result) {
28    if (error) {
29      return notifyFailure(error)
30    }
31    result
32    // {
33    //   sourcesResolved: ["/coffee/foo.coffee"],
34    //   sourcesContent: ["<contents of /coffee/foo.coffee>"]
35    // }
36  })
37})
38
39sourceMapResolve.resolve(code, "/js/foo.js", fs.readFile, function(error, result) {
40  if (error) {
41    return notifyFailure(error)
42  }
43  result
44  // {
45  //   map: {file: "foo.js", mappings: "...", sources: ["/coffee/foo.coffee"], names: []},
46  //   url: "/js/foo.js.map",
47  //   sourcesRelativeTo: "/js/foo.js.map",
48  //   sourceMappingURL: "foo.js.map",
49  //   sourcesResolved: ["/coffee/foo.coffee"],
50  //   sourcesContent: ["<contents of /coffee/foo.coffee>"]
51  // }
52  result.map.sourcesContent = result.sourcesContent
53  var map = new sourceMap.sourceMapConsumer(result.map)
54  map.sourceContentFor("/coffee/foo.coffee")
55  // "<contents of /coffee/foo.coffee>"
56})
57```
58
59
60Installation
61============
62
63- `npm install source-map-resolve`
64- `bower install source-map-resolve`
65- `component install lydell/source-map-resolve`
66
67Works with CommonJS, AMD and browser globals, through UMD.
68
69Note: This module requires `setImmediate` and `atob`.
70Use polyfills if needed, such as:
71
72- <https://github.com/NobleJS/setImmediate>
73- <https://github.com/davidchambers/Base64.js>
74
75
76Usage
77=====
78
79### `sourceMapResolve.resolveSourceMap(code, codeUrl, read, callback)` ###
80
81- `code` is a string of code that may or may not contain a sourceMappingURL
82  comment. Such a comment is used to resolve the source map.
83- `codeUrl` is the url to the file containing `code`. If the sourceMappingURL
84  is relative, it is resolved against `codeUrl`.
85- `read(url, callback)` is a function that reads `url` and responds using
86  `callback(error, content)`. In Node.js you might want to use `fs.readFile`,
87  while in the browser you might want to use an asynchronus `XMLHttpRequest`.
88- `callback(error, result)` is a function that is invoked with either an error
89  or `null` and the result.
90
91The result is an object with the following properties:
92
93- `map`: The source map for `code`, as an object (not a string).
94- `url`: The url to the source map. If the source map came from a data uri,
95  this property is `null`, since then there is no url to it.
96- `sourcesRelativeTo`: The url that the sources of the source map are relative
97  to. Since the sources are relative to the source map, and the url to the
98  source map is provided as the `url` property, this property might seem
99  superfluos. However, remember that the `url` property can be `null` if the
100  source map came from a data uri. If so, the sources are relative to the file
101  containing the data uri—`codeUrl`. This property will be identical to the
102  `url` property or `codeUrl`, whichever is appropriate. This way you can
103  conveniently resolve the sources without having to think about where the
104  source map came from.
105- `sourceMappingURL`: The url of the sourceMappingURL comment in `code`.
106
107If `code` contains no sourceMappingURL, the result is `null`.
108
109### `sourceMapResolve.resolveSources(map, mapUrl, read, [options], callback)` ###
110
111- `map` is a source map, as an object (not a string).
112- `mapUrl` is the url to the file containing `map`. Relative sources in the
113  source map, if any, are resolved against `mapUrl`.
114- `read(url, callback)` is a function that reads `url` and responds using
115  `callback(error, content)`. In Node.js you might want to use `fs.readFile`,
116  while in the browser you might want to use an asynchronus `XMLHttpRequest`.
117- `options` is an optional object with any of the following properties:
118  - `sourceRoot`: Override the `sourceRoot` property of the source map, which
119    might only be relevant when resolving sources in the browser. This lets you
120    bypass it when using the module outside of a browser, if needed. Pass a
121    string to replace the `sourceRoot` property with, or `false` to ignore it.
122    Defaults to `undefined`.
123- `callback(error, result)` is a function that is invoked with either an error
124  or `null` and the result.
125
126The result is an object with the following properties:
127
128- `sourcesResolved`: The same as `map.sources`, except all the sources are
129  fully resolved.
130- `sourcesContent`: An array with the contents of all sources in `map.sources`,
131  in the same order as `map.sources`. If getting the contents of a source fails,
132  an error object is put into the array instead.
133
134### `sourceMapResolve.resolve(code, codeUrl, read, [options], callback)` ###
135
136The arguments are identical to `sourceMapResolve.resolveSourceMap`, except that
137you may also provide the same `options` as in `sourceMapResolve.resolveSources`.
138
139This is a convenience method that first resolves the source map and then its
140sources. You could also do this by first calling
141`sourceMapResolve.resolveSourceMap` and then `sourceMapResolve.resolveSources`.
142
143The result is identical to `sourceMapResolve.resolveSourceMap`, with the
144properties from `sourceMapResolve.resolveSources` merged into it.
145
146There is one extra feature available, though. If `code` is `null`, `codeUrl` is
147treated as a url to the source map instead of to `code`, and will be read. This
148is handy if you _sometimes_ get the source map url from the `SourceMap: <url>`
149header (see the [Notes] section). In this case, the `sourceMappingURL` property
150of the result is `null`.
151
152
153[Notes]: #notes
154
155### `sourceMapResolve.*Sync()` ###
156
157There are also sync versions of the three previous functions. They are identical
158to the async versions, except:
159
160- They expect a sync reading function. In Node.js you might want to use
161  `fs.readFileSync`, while in the browser you might want to use a synchronus
162  `XMLHttpRequest`.
163- They throw errors and return the result instead of using a callback.
164
165`sourceMapResolve.resolveSourcesSync` also accepts `null` as the `read`
166parameter. The result is the same as when passing a function as the `read
167parameter`, except that the `sourcesContent` property of the result will be an
168empty array. In other words, the sources aren’t read. You only get the
169`sourcesResolved` property. (This only supported in the synchronus version, since
170there is no point doing it asynchronusly.)
171
172### `sourceMapResolve.parseMapToJSON(string, [data])` ###
173
174The spec says that if a source map (as a string) starts with `)]}'`, it should
175be stripped off. This is to prevent XSSI attacks. This function does that and
176returns the result of `JSON.parse`ing what’s left.
177
178If this function throws `error`, `error.sourceMapData === data`.
179
180### Errors
181
182All errors passed to callbacks or thrown by this module have a `sourceMapData`
183property that contain as much as possible of the intended result of the function
184up until the error occurred.
185
186Note that while the `map` property of result objects always is an object,
187`error.sourceMapData.map` will be a string if parsing that string fails.
188
189
190Note
191====
192
193This module resolves the source map for a given generated file by looking for a
194sourceMappingURL comment. The spec defines yet a way to provide the URL to the
195source map: By sending the `SourceMap: <url>` header along with the generated
196file. Since this module doesn’t retrive the generated code for you (instead
197_you_ give the generated code to the module), it’s up to you to look for such a
198header when you retrieve the file (should the need arise).
199
200
201Development
202===========
203
204Tests
205-----
206
207First off, run `npm install` to install testing modules and browser polyfills.
208
209`npm test` lints the code and runs the test suite in Node.js.
210
211x-package.json5
212---------------
213
214package.json, component.json and bower.json are all generated from
215x-package.json5 by using [`xpkg`]. Only edit x-package.json5, and remember to
216run `xpkg` before commiting!
217
218[`xpkg`]: https://github.com/kof/node-xpkg
219
220Generating the browser version
221------------------------------
222
223source-map-resolve.js is generated from source-map-resolve-node.js and
224source-map-resolve-template.js. Only edit the two latter files, _not_
225source-map-resolve.js! To generate it, run `npm run build`.
226
227
228License
229=======
230
231[The X11 (“MIT”) License](LICENSE).
232