Creates hash code from string, ported from #C

gistfile1.js

// Borrowed from http://stackoverflow.com/questions/5293174/creating-a-unique-id-from-an-array-of-strings-in-javascript

function getHashCode(str) {
    var h1 = (5381 << 16) + 5381, h2 = h1, index = 0;
    while (index < str.length) {
        h1 = ((h1 << 5) + h1 + (h1 >> 27)) ^ str.charCodeAt(index);
        if (index == str.length - 1) {
            break;
        }
        h2 = ((h2 << 5) + h2 + (h2 >> 27)) ^ str.charCodeAt(index + 1);
        index += 2;
    }

    return h1 + (h2 * 1566083941);
}

To properly match the output of the 32-bit C# version, the return line must be changed:

return h1 + Math.imul(h2, 1566083941) | 0;

The | 0 is necessary to handle addition overflow issues. Without it, a result can be -2905053384 which uses 33 bits, however it would be 1389913912 in a real int type in C# due to overflow. This method also retains 'real' signed integer outputs, just as it should.

Keep in mind this version does not actually match the original GetHashCode output because the original was implemented with UTF-16 strings in mind--two characters per int. But this version is more "sane" or traditional. Also, it's not even that good of a hash function. 🙄