Decode According to the WHATWG Encoding Standard#

This package provides a thin layer on top of iconv-lite which makes it expose some of the same primitives as the Encoding Standard.

const whatwgEncoding = require("whatwg-encoding");

console.assert(whatwgEncoding.labelToName("latin1") === "windows-1252");
console.assert(whatwgEncoding.labelToName("  CYRILLic ") === "ISO-8859-5");

console.assert(whatwgEncoding.isSupported("IBM866") === true);

// Not supported by the Encoding Standard
console.assert(whatwgEncoding.isSupported("UTF-32") === false);

// In the Encoding Standard, but this package can't decode it
console.assert(whatwgEncoding.isSupported("x-mac-cyrillic") === false);

console.assert(whatwgEncoding.getBOMEncoding(new Uint8Array([0xFE, 0xFF])) === "UTF-16BE");
console.assert(whatwgEncoding.getBOMEncoding(new Uint8Array([0x48, 0x69])) === null);

console.assert(whatwgEncoding.decode(new Uint8Array([0x48, 0x69]), "UTF-8") === "Hi");

API#

• decode(uint8Array, fallbackEncodingName): performs the decode algorithm (in which any BOM will override the passed fallback encoding), and returns the resulting string
• labelToName(label): performs the get an encoding algorithm and returns the resulting encoding's name, or null for failure
• isSupported(name): returns whether the encoding is one of the encodings of the Encoding Standard, and is an encoding that this package can decode (via iconv-lite)
• getBOMEncoding(uint8Array): sniffs the first 2–3 bytes of the supplied Uint8Array, returning one of the encoding names "UTF-8", "UTF-16LE", or "UTF-16BE" if the appropriate BOM is present, or null if no BOM is present

Unsupported encodings#

Since we rely on iconv-lite, we are limited to support only the encodings that they support. Currently we are missing support for:

• ISO-2022-JP
• ISO-8859-8-I
• replacement
• x-mac-cyrillic
• x-user-defined

Passing these encoding names will return false when calling isSupported, and passing any of the possible labels for these encodings to labelToName will return null.

Credits#

This package was originally based on the excellent work of @nicolashenry, in jsdom. It has since been pulled out into this separate package.

Alternatives#

If you are looking for a JavaScript implementation of the Encoding Standard's TextEncoder and TextDecoder APIs, you'll want @inexorabletash's text-encoding package. Node.js also has them built-in.