Javascript: create UTF-16 text file?

Question

I have some string need to be a UTF-16 text file. For example:

var s = "aosjdfkzlzkdoaslckjznx";
var file = "data:text/plain;base64," + btoa(s);

This will result a UTF-8 encoding text file. How can I get a UTF-16 text file with string s ?

Answer 1

Related: Javascript to csv export encoding issue

This should do it:

 document.getElementById('download').addEventListener('click', function(){ downloadUtf16('Hello, World', 'myFile.csv') }); function downloadUtf16(str, filename) { // ref: https://stackoverflow.com/q/6226189 var charCode, byteArray = []; // BE BOM byteArray.push(254, 255); // LE BOM // byteArray.push(255, 254); for (var i = 0; i < str.length; ++i) { charCode = str.charCodeAt(i); // BE Bytes byteArray.push((charCode & 0xFF00) >>> 8); byteArray.push(charCode & 0xFF); // LE Bytes // byteArray.push(charCode & 0xff); // byteArray.push(charCode / 256 >>> 0); } var blob = new Blob([new Uint8Array(byteArray)], {type:'text/plain;charset=UTF-16BE;'}); var blobUrl = URL.createObjectURL(blob); // ref: https://stackoverflow.com/a/18197511 var link = document.createElement('a'); link.href = blobUrl; link.download = filename; if (document.createEvent) { var event = document.createEvent('MouseEvents'); event.initEvent('click', true, true); link.dispatchEvent(event); } else { link.click(); } } 

 <button id="download">Download</button> 

Answer 2

You can use a legacy polyfill of the native TextEncoder API to transform a JavaScript string into an ArrayBuffer. As you'll see in that documentation, UTF16 with either endianness is was supported. Libraries that provide UTF-16 support in a Text-Encoder-compatible way will probably appear soon, if they haven't already. Let's assume that one such library exposes a constructor called ExtendedTextEncoder .

Then you can easily create a Blob URL to allow users to download the file, without the inefficient base-64 conversion.

Something like this:

s = "aosjdfkzlzkdoaslckjznx"
var encoder = new ExtendedTextEncoder("utf-16be")
var blob = new Blob(encoder.encode(s), "text/plain")
var url = URL.createObjectURL(blob)

Now you can use url instead of your data: URL.