how to reverse a function js code example

Example 1: javscript .split().reverse.join

"this is a test string".split("").reverse().join("");

Example 2: javascript .split().reverse.join

"this is a test string".split("").reverse().join("");
//"gnirts tset a si siht"
//as a function
function reverseString(string){
return string.split("").reverse().join("");}
reverseString("test string");
//"gnirts tset"