276 lines
10 KiB
Markdown
276 lines
10 KiB
Markdown
# loader-utils
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## Methods
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### `getOptions`
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Recommended way to retrieve the options of a loader invocation:
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```javascript
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// inside your loader
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const options = loaderUtils.getOptions(this);
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```
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1. If `this.query` is a string:
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- Tries to parse the query string and returns a new object
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- Throws if it's not a valid query string
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2. If `this.query` is object-like, it just returns `this.query`
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3. In any other case, it just returns `null`
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**Please note:** The returned `options` object is *read-only*. It may be re-used across multiple invocations.
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If you pass it on to another library, make sure to make a *deep copy* of it:
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```javascript
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const options = Object.assign(
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{},
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defaultOptions,
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loaderUtils.getOptions(this) // it is safe to pass null to Object.assign()
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);
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// don't forget nested objects or arrays
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options.obj = Object.assign({}, options.obj);
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options.arr = options.arr.slice();
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someLibrary(options);
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```
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[clone](https://www.npmjs.com/package/clone) is a good library to make a deep copy of the options.
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#### Options as query strings
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If the loader options have been passed as loader query string (`loader?some¶ms`), the string is parsed by using [`parseQuery`](#parsequery).
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### `parseQuery`
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Parses a passed string (e.g. `loaderContext.resourceQuery`) as a query string, and returns an object.
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``` javascript
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const params = loaderUtils.parseQuery(this.resourceQuery); // resource: `file?param1=foo`
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if (params.param1 === "foo") {
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// do something
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}
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```
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The string is parsed like this:
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``` text
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-> Error
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? -> {}
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?flag -> { flag: true }
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?+flag -> { flag: true }
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?-flag -> { flag: false }
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?xyz=test -> { xyz: "test" }
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?xyz=1 -> { xyz: "1" } // numbers are NOT parsed
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?xyz[]=a -> { xyz: ["a"] }
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?flag1&flag2 -> { flag1: true, flag2: true }
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?+flag1,-flag2 -> { flag1: true, flag2: false }
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?xyz[]=a,xyz[]=b -> { xyz: ["a", "b"] }
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?a%2C%26b=c%2C%26d -> { "a,&b": "c,&d" }
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?{data:{a:1},isJSON5:true} -> { data: { a: 1 }, isJSON5: true }
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```
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### `stringifyRequest`
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Turns a request into a string that can be used inside `require()` or `import` while avoiding absolute paths.
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Use it instead of `JSON.stringify(...)` if you're generating code inside a loader.
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**Why is this necessary?** Since webpack calculates the hash before module paths are translated into module ids, we must avoid absolute paths to ensure
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consistent hashes across different compilations.
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This function:
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- resolves absolute requests into relative requests if the request and the module are on the same hard drive
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- replaces `\` with `/` if the request and the module are on the same hard drive
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- won't change the path at all if the request and the module are on different hard drives
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- applies `JSON.stringify` to the result
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```javascript
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loaderUtils.stringifyRequest(this, "./test.js");
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// "\"./test.js\""
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loaderUtils.stringifyRequest(this, ".\\test.js");
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// "\"./test.js\""
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loaderUtils.stringifyRequest(this, "test");
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// "\"test\""
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loaderUtils.stringifyRequest(this, "test/lib/index.js");
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// "\"test/lib/index.js\""
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loaderUtils.stringifyRequest(this, "otherLoader?andConfig!test?someConfig");
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// "\"otherLoader?andConfig!test?someConfig\""
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loaderUtils.stringifyRequest(this, require.resolve("test"));
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// "\"../node_modules/some-loader/lib/test.js\""
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loaderUtils.stringifyRequest(this, "C:\\module\\test.js");
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// "\"../../test.js\"" (on Windows, in case the module and the request are on the same drive)
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loaderUtils.stringifyRequest(this, "C:\\module\\test.js");
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// "\"C:\\module\\test.js\"" (on Windows, in case the module and the request are on different drives)
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loaderUtils.stringifyRequest(this, "\\\\network-drive\\test.js");
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// "\"\\\\network-drive\\\\test.js\"" (on Windows, in case the module and the request are on different drives)
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```
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### `urlToRequest`
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Converts some resource URL to a webpack module request.
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> i Before call `urlToRequest` you need call `isUrlRequest` to ensure it is requestable url
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```javascript
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const url = "path/to/module.js";
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if (loaderUtils.isUrlRequest(url)) {
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// Logic for requestable url
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const request = loaderUtils.urlToRequest(url);
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} else {
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// Logic for not requestable url
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}
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```
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Simple example:
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```javascript
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const url = "path/to/module.js";
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const request = loaderUtils.urlToRequest(url); // "./path/to/module.js"
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```
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#### Module URLs
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Any URL containing a `~` will be interpreted as a module request. Anything after the `~` will be considered the request path.
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```javascript
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const url = "~path/to/module.js";
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const request = loaderUtils.urlToRequest(url); // "path/to/module.js"
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```
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#### Root-relative URLs
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URLs that are root-relative (start with `/`) can be resolved relative to some arbitrary path by using the `root` parameter:
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```javascript
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const url = "/path/to/module.js";
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const root = "./root";
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const request = loaderUtils.urlToRequest(url, root); // "./root/path/to/module.js"
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```
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To convert a root-relative URL into a module URL, specify a `root` value that starts with `~`:
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```javascript
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const url = "/path/to/module.js";
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const root = "~";
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const request = loaderUtils.urlToRequest(url, root); // "path/to/module.js"
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```
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### `interpolateName`
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Interpolates a filename template using multiple placeholders and/or a regular expression.
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The template and regular expression are set as query params called `name` and `regExp` on the current loader's context.
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```javascript
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const interpolatedName = loaderUtils.interpolateName(loaderContext, name, options);
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```
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The following tokens are replaced in the `name` parameter:
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* `[ext]` the extension of the resource
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* `[name]` the basename of the resource
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* `[path]` the path of the resource relative to the `context` query parameter or option.
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* `[folder]` the folder the resource is in
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* `[query]` the queryof the resource, i.e. `?foo=bar`
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* `[emoji]` a random emoji representation of `options.content`
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* `[emoji:<length>]` same as above, but with a customizable number of emojis
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* `[contenthash]` the hash of `options.content` (Buffer) (by default it's the hex digest of the md4 hash)
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* `[<hashType>:contenthash:<digestType>:<length>]` optionally one can configure
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* other `hashType`s, i. e. `sha1`, `md4`, `md5`, `sha256`, `sha512`
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* other `digestType`s, i. e. `hex`, `base26`, `base32`, `base36`, `base49`, `base52`, `base58`, `base62`, `base64`
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* and `length` the length in chars
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* `[hash]` the hash of `options.content` (Buffer) (by default it's the hex digest of the md4 hash)
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* `[<hashType>:hash:<digestType>:<length>]` optionally one can configure
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* other `hashType`s, i. e. `sha1`, `md4`, `md5`, `sha256`, `sha512`
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* other `digestType`s, i. e. `hex`, `base26`, `base32`, `base36`, `base49`, `base52`, `base58`, `base62`, `base64`
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* and `length` the length in chars
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* `[N]` the N-th match obtained from matching the current file name against `options.regExp`
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In loader context `[hash]` and `[contenthash]` are the same, but we recommend using `[contenthash]` for avoid misleading.
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Examples
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``` javascript
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// loaderContext.resourcePath = "/absolute/path/to/app/js/javascript.js"
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loaderUtils.interpolateName(loaderContext, "js/[hash].script.[ext]", { content: ... });
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// => js/9473fdd0d880a43c21b7778d34872157.script.js
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// loaderContext.resourcePath = "/absolute/path/to/app/js/javascript.js"
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// loaderContext.resourceQuery = "?foo=bar"
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loaderUtils.interpolateName(loaderContext, "js/[hash].script.[ext][query]", { content: ... });
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// => js/9473fdd0d880a43c21b7778d34872157.script.js?foo=bar
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// loaderContext.resourcePath = "/absolute/path/to/app/js/javascript.js"
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loaderUtils.interpolateName(loaderContext, "js/[contenthash].script.[ext]", { content: ... });
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// => js/9473fdd0d880a43c21b7778d34872157.script.js
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// loaderContext.resourcePath = "/absolute/path/to/app/page.html"
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loaderUtils.interpolateName(loaderContext, "html-[hash:6].html", { content: ... });
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// => html-9473fd.html
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// loaderContext.resourcePath = "/absolute/path/to/app/flash.txt"
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loaderUtils.interpolateName(loaderContext, "[hash]", { content: ... });
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// => c31e9820c001c9c4a86bce33ce43b679
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// loaderContext.resourcePath = "/absolute/path/to/app/img/image.gif"
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loaderUtils.interpolateName(loaderContext, "[emoji]", { content: ... });
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// => 👍
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// loaderContext.resourcePath = "/absolute/path/to/app/img/image.gif"
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loaderUtils.interpolateName(loaderContext, "[emoji:4]", { content: ... });
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// => 🙍🏢📤🐝
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// loaderContext.resourcePath = "/absolute/path/to/app/img/image.png"
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loaderUtils.interpolateName(loaderContext, "[sha512:hash:base64:7].[ext]", { content: ... });
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// => 2BKDTjl.png
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// use sha512 hash instead of md4 and with only 7 chars of base64
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// loaderContext.resourcePath = "/absolute/path/to/app/img/myself.png"
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// loaderContext.query.name =
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loaderUtils.interpolateName(loaderContext, "picture.png");
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// => picture.png
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// loaderContext.resourcePath = "/absolute/path/to/app/dir/file.png"
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loaderUtils.interpolateName(loaderContext, "[path][name].[ext]?[hash]", { content: ... });
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// => /app/dir/file.png?9473fdd0d880a43c21b7778d34872157
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// loaderContext.resourcePath = "/absolute/path/to/app/js/page-home.js"
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loaderUtils.interpolateName(loaderContext, "script-[1].[ext]", { regExp: "page-(.*)\\.js", content: ... });
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// => script-home.js
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// loaderContext.resourcePath = "/absolute/path/to/app/js/javascript.js"
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// loaderContext.resourceQuery = "?foo=bar"
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loaderUtils.interpolateName(
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loaderContext,
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(resourcePath, resourceQuery) => {
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// resourcePath - `/app/js/javascript.js`
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// resourceQuery - `?foo=bar`
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return "js/[hash].script.[ext]";
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},
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{ content: ... }
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);
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// => js/9473fdd0d880a43c21b7778d34872157.script.js
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```
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### `getHashDigest`
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``` javascript
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const digestString = loaderUtils.getHashDigest(buffer, hashType, digestType, maxLength);
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```
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* `buffer` the content that should be hashed
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* `hashType` one of `sha1`, `md4`, `md5`, `sha256`, `sha512` or any other node.js supported hash type
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* `digestType` one of `hex`, `base26`, `base32`, `base36`, `base49`, `base52`, `base58`, `base62`, `base64`
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* `maxLength` the maximum length in chars
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## License
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MIT (http://www.opensource.org/licenses/mit-license.php)
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