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- # Adjust Source-map Loader
-
- [![NPM](https://nodei.co/npm/adjust-sourcemap-loader.png)](http://github.com/bholloway/adjust-sourcemap-loader)
-
- Webpack loader that adjusts source maps.
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- Use as a **loader** to debug source-maps or to adjust source-maps between other loaders.
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- Use as a **module filename template** to ensure the final source-map are to your liking.
-
- ## Usage : Loader
-
- ``` javascript
- require('adjust-sourcemap?format=absolute!babel?sourceMap');
- ```
-
- ### Source maps required
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- Note that **source maps** must be enabled on any preceding loader. In the above example we use `babel?sourceMap`.
-
- ### Apply via webpack config
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- It is preferable to adjust your `webpack.config` so to avoid having to prefix every `require()` statement:
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- ``` javascript
- module.exports = {
- module: {
- loaders: [
- {
- test : /\.js/,
- loaders: ['adjust-sourcemap?format=absolute', 'babel?sourceMap']
- }
- ]
- }
- };
- ```
-
- ## Usage : Module filename template
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- Specifying a certain format as the final step in a loader chain will **not** influence the final source format that Webpack will output. Instead the format is determined by the **module filename template**.
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- There are limitations to the filename templating that Webpack provides. This package may also operate as a custom template function that will convert output source-map sources to the desired `format`.
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- In the following example we ensure project-relative source-map sources are output.
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- ```javascript
- var templateFn = require('adjust-sourcemap-loader')
- .moduleFilenameTemplate({
- format: 'projectRelative'
- });
-
- module.exports = {
- output: {
- ...
- devtoolModuleFilenameTemplate : templateFn,
- devtoolFallbackModuleFilenameTemplate: templateFn
- }
- };
- ```
-
- ## Options
-
- As a loader, options may be set using [query parameters](https://webpack.github.io/docs/using-loaders.html#query-parameters) or by using [programmatic parameters](https://webpack.github.io/docs/how-to-write-a-loader.html#programmable-objects-as-query-option). Programmatic means the following in your `webpack.config`.
-
- ```javascript
- module.exports = {
- adjustSourcemapLoader: {
- ...
- }
- }
- ```
-
- Where `...` is a hash of any of the following options.
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- * **`debug`** : `boolean|RegExp` May be used alone (boolean) or with a `RegExp` to match the resource(s) you are interested in debugging.
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- * **`fail`** : `boolean` Implies an **Error** if a source-map source cannot be decoded.
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- * **`format`** : `string` Optional output format for source-map `sources`. Must be the camel-case name of one of the available `codecs`. Omitting the format will result in **no change** and the outgoing source-map will match the incomming one.
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- * **`root`** : `boolean` A boolean flag that indices that a `sourceRoot` path sould be included in the output map. This is contingent on a `format` being specified.
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- * **`codecs`** : `Array.<{name:string, decode:function, encode:function, root:function}>` Optional Array of codecs. There are a number of built-in codecs available. If you specify you own codecs you will loose those that are built-in. However you can include them from the `codec/` directory.
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- Note that **query** parameters take precedence over **programmatic** parameters.
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- ### Changing the format
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- Built-in codecs that may be specified as a `format` include:
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- * `absolute`
- * `outputRelative`
- * `projectRelative`
- * `webpackProtocol`
- * `sourceRelative` (works for loader only, **not** Module filename template)
-
- ### Specifying codecs
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- There are additional built-in codecs that do not support encoding. These are still necessary to decode source-map sources. If you specify your own `options.codecs` then you should **also include the built-in codecs**. Otherwise you will find that some sources cannot be decoded.
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- The existing codecs may be found in `/codec`, or on the loader itself:
-
- ```javascript
- var inBuiltCodecs = require('adjust-sourcemap-loader').codecs,
- myCodecs = [
- {
- name : 'foo',
- decode: function(uri) {...},
- encode: function(absolute) {...},
- root : function() {...}
- },
- ...
- ];
-
- module.exports = {
- adjustSourcemapLoader: {
- codecs: inBuiltCodecs.concat(myCodecs)
- }
- }
- ```
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- The codec **order is important**. Those that come first have precedence. Any codec that detects a distinct URI should be foremost so that illegal paths are not encountered by successive codecs.
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- ### Abstract codecs
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- A codec that detects generated code and cannot `decode()` a URI to an absolute file path.
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- Instead of implementing `encode()` or `root()` it should instead specify `abstract:true`. Its `decode()` function then may return `boolean` where it detects such generated sources.
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- For example, a built-in abstract codec will match the **Webpack bootstrap** code and ensure that its illegal source uri is not encountered by later coders.
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- ## How it works
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- The loader will receive a source map as its second parameter, so long as the preceding loader was using source-maps.
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- The exception is the **css-loader** where the source-map is in the content, which is **not currently supported** .
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- The source-map `sources` are parsed by applying **codec.decode()** functions until one of them returns an absolute path to a file that exists. The exception is abstract codecs, where the source with remain unchanged.
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- If a format is specified then the source-map `sources` are recreated by applying the **codec.encode()** function for the stated `format` and (where the `root` option is specified) the **codec.root()** function will set the source-map `sourceRoot`.
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- If a codec does not specify **codec.encode()** or **codec.root()** then it may **not** be used as the `format`.
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