JSFiddle - React, Tailwind, and code Playground

by Luis Martin

JavaScript

var sym = (...args) => 
	Array.from(new Set([...args[0].filter(el => args[1].indexOf(el) < 0), ...args[1].filter(el => args[0].indexOf(el) < 0)])).sort()
  
var sym = (...args) => 
	args.map(arr => arr.filter(el => args.slice(1).toString().split(",").map(Number).indexOf(el) < 0)).toString().split(",").map(Number)

console.log(sym([1, 2, 3], [5, 2, 1, 4]));