JSFiddle - React, Tailwind, and code Playground

by luka kupunia

JavaScript

function upArray(arr){
  var num = '';
  arr.map(elem => num += elem.toString())
  var result = Array.from(Number(num) + 1); 
  /* return result.slice(0,result.length / 2) */
  console.log(result.slice(0,result.length / 2))
}
upArray([1,2,3,4])