split(), splice(), join() javascript methods usage:
The split() method splits a String object into an array of strings by separating the string into substrings.
The splice() method changes the content of an array by removing existing elements and/or adding new elements.
The join() method joins all elements of an array into a string.
Code:-
var a = "asdasd|dasd|rttewrtert";
var b = a.split('|'); // ["asdasd", "dasd", "rttewrtert"]
var c = b.splice(1); // ["dasd", "rttewrtert"]
var d=b.join(""); // "asdasddasdrttewrtert";
Code:-
<script>
var isPalindrome = function(x) { return x.toString()=== x.toString().split("").reverse().join(""); };
</script>
var res=isPalindrome(121);
console.log(res);
//Output : true
Hope it helps!