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