Convert JavaScript string to UTF-8 bytes in modern browsers using the File API

toutf8.js

// Convert JavaScript string to UTF-8 bytes in modern browsers using the File API
// callback function will be called with UTF8 bytes in Uint8Array
//
// jsPerf test reveals this method is slower than looping over each character.
// http://jsperf.com/convert-javascript-string-to-utf-8-bytes-using-file-api

function toUTF8(string, cb) {
    var reader = new FileReader();
    reader.onload = function(evt) {
        cb(new Uint8Array(reader.result));
    };
    reader.readAsArrayBuffer(new Blob([string]));
}