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    loader-utils
    DefinitelyTyped icon, indicating that this package has TypeScript declarations provided by the separate @types/loader-utils package

    2.0.0 • Public • Published

    loader-utils

    Methods

    getOptions

    Recommended way to retrieve the options of a loader invocation:

    // 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:

    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 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&params), the string is parsed by using parseQuery.

    parseQuery

    Parses a passed string (e.g. loaderContext.resourceQuery) as a query string, and returns an object.

    const params = loaderUtils.parseQuery(this.resourceQuery); // resource: `file?param1=foo`
    if (params.param1 === "foo") {
        // do something
    }

    The string is parsed like this:

                                 -> 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
    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

    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:

    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.

    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:

    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 ~:

    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.

    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 the resource is in
    • [query] the queryof the resource, i.e. ?foo=bar
    • [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 md4 hash)
    • [<hashType>:contenthash:<digestType>:<length>] optionally one can configure
      • other hashTypes, i. e. sha1, md4, md5, sha256, sha512
      • other digestTypes, 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 md4 hash)
    • [<hashType>:hash:<digestType>:<length>] optionally one can configure
      • other hashTypes, i. e. sha1, md4, md5, sha256, sha512
      • other digestTypes, 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

    // loaderContext.resourcePath = "/absolute/path/to/app/js/javascript.js"
    loaderUtils.interpolateName(loaderContext, "js/[hash].script.[ext]", { content: ... });
    // => js/9473fdd0d880a43c21b7778d34872157.script.js
     
    // loaderContext.resourcePath = "/absolute/path/to/app/js/javascript.js"
    // loaderContext.resourceQuery = "?foo=bar"
    loaderUtils.interpolateName(loaderContext, "js/[hash].script.[ext][query]", { content: ... });
    // => js/9473fdd0d880a43c21b7778d34872157.script.js?foo=bar
     
    // loaderContext.resourcePath = "/absolute/path/to/app/js/javascript.js"
    loaderUtils.interpolateName(loaderContext, "js/[contenthash].script.[ext]", { content: ... });
    // => js/9473fdd0d880a43c21b7778d34872157.script.js
     
    // loaderContext.resourcePath = "/absolute/path/to/app/page.html"
    loaderUtils.interpolateName(loaderContext, "html-[hash:6].html", { content: ... });
    // => html-9473fd.html
     
    // loaderContext.resourcePath = "/absolute/path/to/app/flash.txt"
    loaderUtils.interpolateName(loaderContext, "[hash]", { content: ... });
    // => c31e9820c001c9c4a86bce33ce43b679
     
    // loaderContext.resourcePath = "/absolute/path/to/app/img/image.gif"
    loaderUtils.interpolateName(loaderContext, "[emoji]", { content: ... });
    // => 👍
     
    // loaderContext.resourcePath = "/absolute/path/to/app/img/image.gif"
    loaderUtils.interpolateName(loaderContext, "[emoji:4]", { content: ... });
    // => 🙍🏢📤🐝
     
    // loaderContext.resourcePath = "/absolute/path/to/app/img/image.png"
    loaderUtils.interpolateName(loaderContext, "[sha512:hash:base64:7].[ext]", { content: ... });
    // => 2BKDTjl.png
    // use sha512 hash instead of md4 and with only 7 chars of base64
     
    // loaderContext.resourcePath = "/absolute/path/to/app/img/myself.png"
    // loaderContext.query.name =
    loaderUtils.interpolateName(loaderContext, "picture.png");
    // => picture.png
     
    // loaderContext.resourcePath = "/absolute/path/to/app/dir/file.png"
    loaderUtils.interpolateName(loaderContext, "[path][name].[ext]?[hash]", { content: ... });
    // => /app/dir/file.png?9473fdd0d880a43c21b7778d34872157
     
    // loaderContext.resourcePath = "/absolute/path/to/app/js/page-home.js"
    loaderUtils.interpolateName(loaderContext, "script-[1].[ext]", { regExp: "page-(.*)\\.js", content: ... });
    // => script-home.js
     
    // loaderContext.resourcePath = "/absolute/path/to/app/js/javascript.js"
    // loaderContext.resourceQuery = "?foo=bar"
    loaderUtils.interpolateName(
      loaderContext, 
      (resourcePath, resourceQuery) => { 
        // resourcePath - `/app/js/javascript.js`
        // resourceQuery - `?foo=bar`
     
        return "js/[hash].script.[ext]"; 
      }, 
      { content: ... }
    );
    // => js/9473fdd0d880a43c21b7778d34872157.script.js

    getHashDigest

    const digestString = loaderUtils.getHashDigest(buffer, hashType, digestType, maxLength);
    • buffer the content that should be hashed
    • hashType one of sha1, md4, 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)

    Keywords

    none

    Install

    npm i loader-utils

    DownloadsWeekly Downloads

    34,792,337

    Version

    2.0.0

    License

    MIT

    Unpacked Size

    29.5 kB

    Total Files

    15

    Last publish

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