hashcode/hashcode.js

hashcode implementation by Stuart Bannerman (https://github.com/stuartbannerman/hashcode) packaged as npm-module.

/*
 * Hashcode.js 1.0.2
 * https://github.com/stuartbannerman/hashcode
 *
 * Copyright 2013 Stuart Bannerman (me@stuartbannerman.com)    
 * Released under the MIT license
 *
 * Date: 07-04-2013
 *
 * packaged as npm module by
 * A. Siebert, ask@touchableheroes.com
 *
 * usage:
 * ------------------------------------
 * var encode = require( 'hashcode' ).hashCode;
 * var hash = encode().value( "my string value" ); 
 */
exports.hashCode = function () {

    // Hashes a string
    var hash = function (string) {
        var string = string.toString(), hash = 0, i;
        for (i = 0; i < string.length; i++) {
            hash = (((hash << 5) - hash) + string.charCodeAt(i)) & 0xFFFFFFFF;
        }

        return hash;
    };
    // Deep hashes an object
    var object = function (obj) {
        var result = 0;
        for (var property in obj) {
            if (obj.hasOwnProperty(property)) {
                result += hash(property + value(obj[property]));
            }
        }

        return result;
    };
    // Does a type check on the passed in value and calls the appropriate hash method
    var value = function (value) {
        var types =
        {
            'string': hash,
            'number': hash,
            'boolean': hash,
            'object': object
            // functions are excluded because they are not representative of the state of an object
            // types 'undefined' or 'null' will have a hash of 0
        };
        var type = typeof value;

        return value != null && types[type] ? types[type](value) + hash(type) : 0;
    };

    return {
        value: value
    };
};