how to import js to js code example

Example 1: include other js files in a js file

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

Example 2: import javascript

/*Imagine a file called math_functions.js that contains several functions
related to mathematical operations. One of them is stored in a variable called
add.*/

//If you want to import one item:
import { add } from './math_functions.js';

//If you want to import multiple items:
import { add, someothervariable } from './math_functions.js';