TextDecoder

Baseline Widely available

This feature is well established and works across many devices and browser versions. It’s been available across browsers since January 2020.

Note: This feature is available in Web Workers.

The TextDecoder interface represents a decoder for a specific text encoding, such as UTF-8, ISO-8859-2, or GBK. A decoder takes an array of bytes as input and returns a JavaScript string.

Constructor

TextDecoder()

Creates and returns a new TextDecoder.

Instance properties

The TextDecoder interface doesn't inherit any properties.

TextDecoder.encoding Read only

A string containing the name of the character encoding system that this TextDecoder will use.

TextDecoder.fatal Read only

A boolean indicating whether the error mode is fatal.

TextDecoder.ignoreBOM Read only

A boolean indicating whether the byte order mark is ignored.

Instance methods

The TextDecoder interface doesn't inherit any methods.

TextDecoder.decode()

Decodes the given bytes into a JavaScript string and returns it.

Examples

Decoding UTF-8 text

This example shows how to decode the UTF-8 encoding of the character "𠮷".

html
<button id="decode">Decode</button>
<button id="reset">Reset</button>
<div id="output"></div>

div {
  margin: 1rem 0;
}

js
const utf8decoder = new TextDecoder(); // default 'utf-8'
const encodedText = new Uint8Array([240, 160, 174, 183]);

const output = document.querySelector("#output");
const decodeButton = document.querySelector("#decode");
decodeButton.addEventListener("click", () => {
  output.textContent = utf8decoder.decode(encodedText);
});

const resetButton = document.querySelector("#reset");
resetButton.addEventListener("click", () => {
  window.location.reload();
});

Decoding non-UTF8 text

In this example, we decode the Russian text "Привет, мир!", which means "Hello, world." In our TextDecoder() constructor, we specify the Windows-1251 character encoding.

html
<button id="decode">Decode</button>
<button id="reset">Reset</button>
<div id="decoded"></div>

div {
  margin: 1rem 0;
}

js
const win1251decoder = new TextDecoder("windows-1251");
const encodedText = new Uint8Array([
  207, 240, 232, 226, 229, 242, 44, 32, 236, 232, 240, 33,
]);

const decoded = document.querySelector("#decoded");
const decodeButton = document.querySelector("#decode");
decodeButton.addEventListener("click", () => {
  decoded.textContent = win1251decoder.decode(encodedText);
});

const resetButton = document.querySelector("#reset");
resetButton.addEventListener("click", () => {
  window.location.reload();
});