Simple Java Script object hashing

Hashify.js

/**
  * @description Simple hashing for JS objects
  * @author Gabriel Dewes at 9 nov, 2016
  */
Object.prototype.hashify = function(obj, len) {
   obj = obj || this;
   len = len || 2;
   var i, j, r=[];
   for (i=0; i<len; i++) {
     r.push(i*268803292);
   }
   obj = stringify(obj);
   for (i=0; i<obj.length; i++) {
     for (j=0; j<r.length; j++) {
       r[j] = (r[j] << 13) - (r[j] >> 19);
       r[j] += obj.charCodeAt(i) << (r[j] % 24);
       r[j] = r[j] & r[j];
     }
   }
   for (i=0; i<r.length; i++) {
     r[i] = r[i].toHex();
   }
   return r.join('');
 };

 function stringify(obj) {
   var i, r;
   if (obj === null) return 'null';
   if (obj === true) return 'true';
   if (obj === false) return 'false';

   i = typeof obj;
   if (i === 'string') return 'string:'+ obj.replace(/([\\\\;])/g,'\\$1');
   if (i === 'number') return 'number:'+ obj.toString().replace(/([\\\\;])/g,'\\$1');

   if (obj instanceof Date) return 'date:'+ obj;
   if (obj instanceof Function) return 'function:'+ obj.toString().replace(/([\\\\;])/g,'\\$1');
   if (obj instanceof Array) {
     r=[];
     for (i=0; i<obj.length; i++) {
       r.push(stringify(obj[i]));
     }
     return 'array:'+ r.join(',');
   }
   r=[];
   for (i in obj) {
     r.push(i +':'+ stringify(obj[i]));
   }
   return 'object:'+ r[0];
 };

 Number.prototype.toHex = function () {
   var ret = ((this < 0 ? 0x8 : 0) +
             ((this >> 28) & 0x7)).toString(16) +
             (this & 0xfffffff).toString(16);
   while (ret.length < 8) ret = '0'+ ret;
   return ret;
 };

var a = [
  {g:1, a:'2', b:[3]},
  10,
  ['g',4,'b','r',1,'e','l'],
  "gabriel",
  new Date(),
  function(){return true;},
  50.34,
  null,
  true,
  false
],
console.log(a.hashify() === hashify(a));