How can I delete using INNER JOIN with SQL Server?

Add 2 numbers leetcode issue

Smith

var addTwoNumbers = function(l1, l2) {
  l1.reverse();
  l2.reverse();
  let l1temp = '';
  let l2temp = '';
  const array = [];
  for (let i = 0; i < l1.length; i++) {
    l1temp.concat(l1[i]);
  }

  parseInt(l1temp);

  for (let i = 0; i < l2.length; i++) {
    l2temp.concat(l2[i]);
  }

  parseInt(l2temp);

  var hello = l2temp + l1temp;
  hello.split("").reverse().join("")
  array = hello.split('')
  return array

};

so im getting a runtime error saying that reverse isn't a function? on line 2???

btw i have syntaxed it properly using tab but it doesnt show on here.