JSON.stringify([1,2,3].sort()) === JSON.stringify([3,2,1].sort());

[1,2,3].sort().toString() === [3,2,1].sort().toString();

let cmp = ( x, y ) => {// If both x and y are null or undefined and exactly the same if ( x === y ) {  return true; }// If they are not strictly equal, they both need to be Objects if ( ! ( x instanceof Object ) || ! ( y instanceof Object ) ) {  return false; }//They must have the exact same prototype chain,the closest we can do is//test the constructor. if ( x.constructor !== y.constructor ) {  return false; } for ( var p in x ) {  //Inherited properties were tested using x.constructor === y.constructor  if ( x.hasOwnProperty( p ) ) {  // Allows comparing x[ p ] and y[ p ] when set to undefined  if ( ! y.hasOwnProperty( p ) ) {   return false;  }  // If they have the same strict value or identity then they are equal  if ( x[ p ] === y[ p ] ) {   continue;  }  // Numbers, Strings, Functions, Booleans must be strictly equal  if ( typeof( x[ p ] ) !== "object" ) {   return false;  }  // Objects and Arrays must be tested recursively  if ( ! Object.equals( x[ p ], y[ p ] ) ) {   return false;  }  } } for ( p in y ) {  // allows x[ p ] to be set to undefined  if ( y.hasOwnProperty( p ) && ! x.hasOwnProperty( p ) ) {  return false;  } } return true;};

// 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;}