Reverse a String in Javascript - Competitive Programming Interview Question and Solution

Here are three ways to reverse a string in javascript

Iterate through string in reverse order and push letters to array, then join the array

function reverse1(str) {
  if(!str || str.length < 2 || typeof str !== "string") {
    return new Error("Not a valid input");
  }
  const backwards = [];
  for (let i = str.length; i > -1; i--) {
    backwards.push(str[i]);
  }
  return backwards.join('');
}

Use split, reverse, and join methods

function reverse2(str) {
  return str.split().reverse().join();
}

Use ES6 arroe function and spread operator to copy as well as convert the string to array and then reverse and join

reverse3 = str => [...str].reverse().join('');

Call the three functions

console.log(reverse1("Hello World!"));
console.log(reverse2("Hello World!"));
console.log(reverse3("Hello World!"));

Output

!dlroW olleH
Hello World!
!dlroW olleH