js create hash code example

Example 1: javascript hash string

/**
 * Calculate a 32 bit FNV-1a hash
 * Found here: https://gist.github.com/vaiorabbit/5657561
 * Ref.: http://isthe.com/chongo/tech/comp/fnv/
 *
 * @param {string} str the input value
 * @param {boolean} [asString=false] set to true to return the hash value as 
 *     8-digit hex string instead of an integer
 * @param {integer} [seed] optionally pass the hash of the previous chunk
 * @returns {integer | string}
 */
function hashFnv32a(str, asString, seed) {
    /*jshint bitwise:false */
    var i, l,
        hval = (seed === undefined) ? 0x811c9dc5 : seed;

    for (i = 0, l = str.length; i < l; i++) {
        hval ^= str.charCodeAt(i);
        hval += (hval << 1) + (hval << 4) + (hval << 7) + (hval << 8) + (hval << 24);
    }
    if( asString ){
        // Convert to 8 digit hex string
        return ("0000000" + (hval >>> 0).toString(16)).substr(-8);
    }
    return hval >>> 0;
}

Example 2: java script hash

function hashFnv32a(str, asString, seed) {
    /*jshint bitwise:false */
    var i, l,
        hval = (seed === undefined) ? 0x811c9dc5 : seed;

    for (i = 0, l = str.length; i < l; i++) {
        hval ^= str.charCodeAt(i);
        hval += (hval << 1) + (hval << 4) + (hval << 7) + (hval << 8) + (hval << 24);
    }
    if( asString ){
        // Convert to 8 digit hex string
        return ("0000000" + (hval >>> 0).toString(16)).substr(-8);
    }
    return hval >>> 0;
}

Example 3: How to use hash in javascript

function HashTable(obj)
{
    this.length = 0;
    this.items = {};
    for (var p in obj) {
        if (obj.hasOwnProperty(p)) {
            this.items[p] = obj[p];
            this.length++;
        }
    }

    this.setItem = function(key, value)
    {
        var previous = undefined;
        if (this.hasItem(key)) {
            previous = this.items[key];
          	return previous;
        }
        else {
            this.length++;
        }
        this.items[key] = value;
        return previous;
    }

    this.getItem = function(key) {
        return this.hasItem(key) ? this.items[key] : undefined;
    }

    this.hasItem = function(key)
    {
        return this.items.hasOwnProperty(key);
    }
   
    this.removeItem = function(key)
    {
        if (this.hasItem(key)) {
            previous = this.items[key];
            this.length--;
            delete this.items[key];
            return previous;
        }
        else {
            return undefined;
        }
    }

    this.keys = function()
    {
        var keys = [];
        for (var k in this.items) {
            if (this.hasItem(k)) {
                keys.push(k);
            }
        }
        return keys;
    }

    this.values = function()
    {
        var values = [];
        for (var k in this.items) {
            if (this.hasItem(k)) {
                values.push(this.items[k]);
            }
        }
        return values;
    }

    this.each = function(fn) {
        for (var k in this.items) {
            if (this.hasItem(k)) {
                fn(k, this.items[k]);
            }
        }
    }

    this.clear = function()
    {
        this.items = {}
        this.length = 0;
    }
}

Example 4: How to use hash in javascript

var h = new Object(); // or just {}
h['one'] = 1;
h['two'] = 2;
h['three'] = 3;

// show the values stored
for (var k in h) {
    // use hasOwnProperty to filter out keys from the Object.prototype
    if (h.hasOwnProperty(k)) {
        alert('key is: ' + k + ', value is: ' + h[k]);
    }
}