unraw

unraw("\\'\\t\\u{1f601}\\'"); // -> "'	😁'"

unraw is a small module that converts raw strings to parsed strings in the same manner as the standard JavaScript escaping engine. In essence, it is the exact opposite of String.raw.

Use Case

Most of the time, you probably don't need this library unless you're working directly with raw strings and you need a way to get them back to normal strings. Maybe the most signicant use case is when building template literal tags; you can use the .raw property of the passed string array to access the raw strings, but then you may want to still return normal strings after processing.

The module is also useful for parsing text files written with escape sequences, although keep in mind that the JavaScript flavor of escape sequences may differ from the flavor used in an input file.

Getting Started

unraw is a UMD module, so it can be used in Node or on the web. Typings are included for TypeScript as well.

Usage in Node.JS

unraw is hosted on npm, so you can install with:

npm i unraw

To use in code:

import unraw from "unraw";

unraw("\\n");

If you want to access error messages:

import {unraw, errorMessages, ErrorType} from "unraw";

unraw("\\n");
errorMessages.get(ErrorType.MalformedUnicode);

Usage in the Browser

You can embed it (minified) on a webpage with RequireJS. The module is available on UNPKG at https://unpkg.com/unraw:

<script src="https://cdnjs.cloudflare.com/ajax/libs/require.js/2.3.6/require.min.js"></script>
<script>
  require(["https://unpkg.com/unraw^1.2.3/dist/index.min.js"], function(unraw) {
    unraw.unraw("\\n");
    unraw.errorMessages.get(unraw.ErrorType.MalformedUnicode);
  });
</script>

Note: Importing via the 'bare' url (https://unpkg.com/unraw) is not supported as it breaks references to other required files.

Usage

Usage is simple - the library exports a default function, unraw. The first argument to unraw is the string to parse, and the second is an optional flag to allow or disallow octal escapes, which are deprecated (defaults to false, so the default behavior is to throw an error when octal sequences are encountered).

unraw("\\t\\tThis is indented.");
// => "		This is indented."

The library attempts to mimic the behaviour of standard JavaScript strings as closely as possible. This means that invalid escape sequences will throw SyntaxErrors and that every escape sequence that is valid in a normal string should be valid when passed to unraw.

In some ways this is similar to the behavior of JSON.parse.

You can always expect the outcome of calling unraw on a raw string to be exactly the same as if that string were not raw in the first place:

`Invalid: \u23`                   // Throws a SyntaxError
unraw(String.raw`Invalid: \u23`)  // Throws a SyntaxError

`Valid: \u0041`                   // => `Valid: A`
unraw(String.raw`Valid: \u0041`)  // => `Valid: A`

`Valid: \A`                       // => `Valid: A`
unraw(String.raw`Valid: \A`)      // => `Valid: A`

`Valid: \\`                       // => `Valid: \`
unraw(String.raw`Valid: \\`)      // => `Valid: \`

`Valid: \x42`                     // => `Valid: B`
unraw(String.raw`Valid: \x42`)    // => `Valid: B`

`Octal: \102`                      // => Throws a SyntaxError
unraw(String.raw`Octal: \102`)     // => Throws a SyntaxError
unraw(String.raw`Octal: \102`, true) // => Octal: B

Errors

If desired, you can access the possible error messages to help identify errors:

import {unraw, ErrorType, errorMessages} from "unraw";

try {
  unraw("\\u25");
} catch (err) {
  if (err.message === errorMessages.get(ErrorType.MalformedUnicode)) {
    console.error("String had an invalid Unicode escape sequence.");
  }
}

The full list of error message names available through the ErrorType enum (exposed as a normal object in JavaScript).

Contributing

Found a bug? Please, submit it here.

Pull requests are always welcome, although to increase your chances of your contribution being accepted, opening an issue and linking to it is always a good idea.

Pull requests will not be merged unless the Azure Pipelines build succeeds. This means that all checks must pass and code must be free of lint errors. To quickly confirm that it will, just run:

npm run check

This checks your formatting, tests, and for TypeScript compiler errors. If the task doesn't fail, you should be good to go.

Other Tasks

For your convenience, some other tasks are also provided in the package.json:

• npm run build - Compiles TypeScript code to JavaScript
• npm run minify - Generate minified JavaScript files from compiled files
• npm run test - Quickly run tests using TypeScript code without compiling
• npm run testWithCoverage - Run tests and generate coverage report
• npm run lint - Check code for linting errors
• npm run check - Check to ensure code will pass Pipelines checks (see above)
• npm run format - Format code using Prettier