alert([]==[]);  // falsealert([]===[]);  // false

JSON.stringify(a1) == JSON.stringify(a2)

a1.toString() == a2.toString()

// Warn if overriding existing methodif(Array.prototype.equals)  console.warn("Overriding existing Array.prototype.equals. Possible causes: New API defines the method, there's a framework conflict or you've got double inclusions in your code.");// attach the .equals method to Array's prototype to call it on any arrayArray.prototype.equals = function (array) {  // if the other array is a falsy value, return  if (!array)    return false;  // compare lengths - can save a lot of time   if (this.length != array.length)    return false;  for (var i = 0, l = this.length; i < l; i++) {    // Check if we have nested arrays    if (this[i] instanceof Array && array[i] instanceof Array) {      // recurse into the nested arrays      if (!this[i].equals(array[i]))        return false;        }          else if (this[i] != array[i]) {       // Warning - two different object instances will never be equal: {x:20} != {x:20}      return false;      }        }      return true;}// Hide method from for-in loopsObject.defineProperty(Array.prototype, "equals", {enumerable: false});

Object.prototype.equals = function(object2) {  //For the first loop, we only check for types  for (propName in this) {    //Check for inherited methods and properties - like .equals itself    //https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/hasOwnProperty    //Return false if the return value is different    if (this.hasOwnProperty(propName) != object2.hasOwnProperty(propName)) {      return false;    }    //Check instance type    else if (typeof this[propName] != typeof object2[propName]) {      //Different types => not equal      return false;    }  }  //Now a deeper check using other objects property names  for(propName in object2) {    //We must check instances anyway, there may be a property that only exists in object2      //I wonder, if remembering the checked values from the first loop would be faster or not     if (this.hasOwnProperty(propName) != object2.hasOwnProperty(propName)) {      return false;    }    else if (typeof this[propName] != typeof object2[propName]) {      return false;    }    //If the property is inherited, do not check any more (it must be equa if both objects inherit it)    if(!this.hasOwnProperty(propName))     continue;    //Now the detail check and recursion    //This returns the script back to the array comparing    /**REQUIRES Array.equals**/    if (this[propName] instanceof Array && object2[propName] instanceof Array) {          // recurse into the nested arrays      if (!this[propName].equals(object2[propName]))            return false;    }    else if (this[propName] instanceof Object && object2[propName] instanceof Object) {          // recurse into another objects          //console.log("Recursing to compare ", this[propName],"with",object2[propName], " both named /""+propName+"/"");      if (!this[propName].equals(object2[propName]))            return false;    }    //Normal value comparison for strings and numbers    else if(this[propName] != object2[propName]) {      return false;    }  }  //If everything passed, let's say YES  return true;}