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

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

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;};