JSFiddle - React, Tailwind, and code Playground

JavaScript

var list = [1, 2, 4, 4];
var sum = 8;
var sum_array = [];

for (var i = 0; i < list.length - 1; i++) {
	for (var j = i + 1; j < list.length; j++) {
  	if (list[i] + list[j] === sum) {
    	sum_array.push(list[i], list[j]);
    }
  }
}

alert(sum_array);