gistfile1.js

var crc32;
(function(){
    var crcTableTable = [];
    function buildTable(polynomial) {
        var table = [];
        function reverse(x, n) {
            var b = 0;
            while (n) {
                b = b * 2 + x % 2;
                x /= 2;
                x -= x % 1;
                n--;
            }
            return b;
        }

        for (i = 255; i >= 0; i--) {
            c = reverse(i, 32);

            for (j = 0; j < 8; j++) {
                c = ((c * 2) ^ (((c >>> 31) % 2) * polynomial)) >>> 0;
            }

            table[i] = reverse(c, 32);
        }
        
        return table;
    }

    crc32 = function(s/*, polynomial = 0x04C11DB7, initialValue = 0xFFFFFFFF, finalXORValue = 0xFFFFFFFF*/) {
        s = String(s);
        var polynomial = arguments.length < 2 ? 0x04C11DB7 : arguments[1];
        var initialValue = arguments.length < 3 ? 0xFFFFFFFF : arguments[2];
        var finalXORValue = arguments.length < 4 ? 0xFFFFFFFF : arguments[3];
        var crc = initialValue;
        var table = [];
        var i;
        var j;
        var c;

        if(crcTableTable[polynomial]) {
            table = crcTableTable[polynomial]
        } else {
            table = crcTableTable[polynomial] = buildTable(polynomial);
        }

        for (i = 0; i < s.length; i++) {
            c = s.charCodeAt(i);
            if (c > 255) {
                throw new RangeError();
            }
            j = (crc % 256) ^ c;
            crc = ((crc / 256) ^ table[j]) >>> 0;
        }

        return (crc ^ finalXORValue) >>> 0;
    };
})()

alert(crc32('test').toString(16));//D87F7E0C
alert(crc32('test', 0x04c11db7, 0, 0xFFFFFFFF).toString(16));//6C45EEF
alert(crc32('test', 0x04c11db7, 0xFFFFFFFF, 0).toString(16));//278081F3
alert(crc32('test', 0x04c11db7, 0, 0).toString(16));//F93BA110

cached the crc table to enhance the performance