How can I join an array of numbers into 1 concatenated number?

Question

How do I join this array to give me expected output in as few steps as possible?

var x = [31,31,3,1]
//expected output: x = 313131;

Answer 1

Javascript join() will give you the expected output as string. If you want it as a number, do this:

var x = [31,31,3,1];
var xAsString = x.join(''); // Results in a string
var xAsNumber = Number(x.join('')); // Results in a number, you can also use +(x.join(''))