javascript string hashing [benchmark]

  Benchmark.prototype.setup = function() {
    function bitwise(str){
        var hash = 0;
        if (str.length == 0) return hash;
        for (i = 0; i < str.length; i++) {
            char = str.charCodeAt(i);
            hash = ((hash<<5)-hash)+char;
        }
        return hash;
    }

    function numbers(str) {
       var res = 0,
           len = str.length;
       for (var i = 0; i < len; i++) {
        res = res * 31 + str.charCodeAt(i);
       }
       return res;
      }

    function bitwiseconv(str){
        var hash = 0;
        if (str.length == 0) return hash;
        for (i = 0; i < str.length; i++) {
            char = str.charCodeAt(i);
            hash = ((hash<<5)-hash)+char;
            hash = hash & hash; // Convert to 32bit integer
        }
        return hash;
    }

    function numbersconv(str) {
       var res = 0,
           len = str.length;
       for (var i = 0; i < len; i++) {
        res = res * 31 + str.charCodeAt(i);
        res = res & res;
       }
       return res;
      }

    function murmurhash3_32_gc(key, seed) {
        var remainder, bytes, h1, h1b, c1, c1b, c2, c2b, k1, i;

        remainder = key.length & 3; // key.length % 4
        bytes = key.length - remainder;
        h1 = seed;
        c1 = 0xcc9e2d51;
        c2 = 0x1b873593;
        i = 0;

        while (i < bytes) {
                k1 =
                  ((key.charCodeAt(i) & 0xff)) |
                  ((key.charCodeAt(++i) & 0xff) << 8) |
                  ((key.charCodeAt(++i) & 0xff) << 16) |
                  ((key.charCodeAt(++i) & 0xff) << 24);
                ++i;

                k1 = ((((k1 & 0xffff) * c1) + ((((k1 >>> 16) * c1) & 0xffff) << 16))) & 0xffffffff;
                k1 = (k1 << 15) | (k1 >>> 17);
                k1 = ((((k1 & 0xffff) * c2) + ((((k1 >>> 16) * c2) & 0xffff) << 16))) & 0xffffffff;

                h1 ^= k1;
            h1 = (h1 << 13) | (h1 >>> 19);
                h1b = ((((h1 & 0xffff) * 5) + ((((h1 >>> 16) * 5) & 0xffff) << 16))) & 0xffffffff;
                h1 = (((h1b & 0xffff) + 0x6b64) + ((((h1b >>> 16) + 0xe654) & 0xffff) << 16));
        }

        k1 = 0;

        switch (remainder) {
                case 3: k1 ^= (key.charCodeAt(i + 2) & 0xff) << 16;
                case 2: k1 ^= (key.charCodeAt(i + 1) & 0xff) << 8;
                case 1: k1 ^= (key.charCodeAt(i) & 0xff);

                k1 = (((k1 & 0xffff) * c1) + ((((k1 >>> 16) * c1) & 0xffff) << 16)) & 0xffffffff;
                k1 = (k1 << 15) | (k1 >>> 17);
                k1 = (((k1 & 0xffff) * c2) + ((((k1 >>> 16) * c2) & 0xffff) << 16)) & 0xffffffff;
                h1 ^= k1;
        }

        h1 ^= key.length;

        h1 ^= h1 >>> 16;
        h1 = (((h1 & 0xffff) * 0x85ebca6b) + ((((h1 >>> 16) * 0x85ebca6b) & 0xffff) << 16)) & 0xffffffff;
        h1 ^= h1 >>> 13;
        h1 = ((((h1 & 0xffff) * 0xc2b2ae35) + ((((h1 >>> 16) * 0xc2b2ae35) & 0xffff) << 16))) & 0xffffffff;
        h1 ^= h1 >>> 16;

        return h1 >>> 0;
    }

  };