JSFiddle - React, Tailwind, and code Playground

HTML

<h1>Here be dragons</h1>
<ul id="results"></ul>

JavaScript

var arraySlice = function (array) {
    return Array.slice(array, 0);
};

var convertToByteString = function (array) {
   var len = (array.length + 9999) / 10000;
   var str = '';
   var f = String.fromCharCode;
   var off, i;
   for (i = 0; i < len; i++) {
       off = i * 10000;
       str += f.apply(null, array.subarray(off, off + 10000));
   }
   return str;
};
    
var timeIt = function (message, conversionFunc) {
    var start = (new Date()).getTime();
    var size = 750 * 500 * 4;
        
    // this many frames per second ;)
    for (var i = 0; i < 30; i ++) {
        var x = conversionFunc(new Uint8ClampedArray(size));
    }
    
    var end = (new Date()).getTime();
    $('<li></li>').text(message + ' took ' + (end - start) + 'ms')
        .appendTo('#results');
};

timeIt('Array.slice', arraySlice);
timeIt('String.fromCharCode multiple times', convertToByteString);