javascript using another js file

1document.writeln("<script type='text/javascript' src='Script1.js'></script>");
2document.writeln("<script type='text/javascript' src='Script2.js'></script>");

1// module.js
2export function hello() {
3  return "Hello";
4}
5
6// main.js
7import {hello} from 'module'; // or './module'
8let val = hello(); // val is "Hello";