shorthash.js

// Author: Allex Wang ([email protected])
// GistID: 9b821248c36787ba66c0
// GistURL: https://gist.github.com/9b821248c36787ba66c0

// refer to: http://werxltd.com/wp/2010/05/13/javascript-implementation-of-javas-string-hashcode-method/
function bitwise(str) {
    var hash = 0;
    if (str.length == 0) return hash;
    for (var i = 0; i < str.length; i++) {
        var ch = str.charCodeAt(i);
        hash = ((hash << 5) - hash) + ch;
        hash = hash & hash; // Convert to 32bit integer
    }
    return hash;
}

// convert 10 binary to customized binary, max is 62
function binaryTransfer(integer, binary) {
    binary = binary || 62;
    var stack = [];
    var num;
    var result = '';
    var sign = integer < 0 ? '-' : '';
    
    function table (num) {
        var t = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';
        return t[num];
    }
    
    integer = Math.abs(integer);
    
    while (integer >= binary) {
        num = integer % binary;
        integer = Math.floor(integer / binary);
        stack.push(table(num));
    }
    
    if (integer > 0) {
        stack.push(table(integer));
    }

    for (var i = stack.length - 1; i >= 0; i--) {
        result += stack[i];
    }

    return sign + result;
}

/**
 * why choose 61 binary, because we need the last element char to replace the minus sign
 * eg: -aGtzd will be ZaGtzd
 */
function unique (text) {
    var id = binaryTransfer(bitwise(text), 61);
    return id.replace('-', 'Z');
}

exports.bitwise = bitwise;
exports.binaryTransfer = binaryTransfer;
exports.unique = unique;

Hi Allex, Nice Work!! I'm using your code but I need to generate a 5 chars Hash using 'abcdefghijklmnopqrstuvwxyz'. Have you any suggestion that can help me to accomplish that?. Thanks