export

    //  
    export let name1, name2, , nameN; // var, const 
    export let name1 = , name2 = , , nameN; // var, const 
    export function functionName(){...}
    export class ClassName {...}

    //  
    export { name1, name2, , nameN };

    //   
    export { variable1 as name1, variable2 as name2, , nameN };

    //  
    export const { name1, name2: bar } = o;

    //  
    export default expression;
    export default function () {  } // also class, function*
    export default function name1() {  } // also class, function*
    export { name1 as default,  };

    //  
    export * from ; // does not set the default export
    export * as name1 from ;
    export { name1, name2, , nameN } from ;
    export { import1 as name1, import2 as name2, , nameN } from ;
    export { default } from ;

// test.js
let k;
export default (k = 12);

//   
import m from "./test"; // k  ,   k  m   
console.log(m); // 12 

export { myFunction as function1, myVariable as variable };

export foo from "bar.js";

import foo from 'bar.js';
export foo;

// module "my-module.js"
function cube(x) {
  return x * x * x;
}
const foo = Math.PI + Math.SQRT2;
var graph = {
  options: {
    color: "white",
    thickness: "2px",
  },
  draw: function () {
    console.log("From graph draw function");
  },
};
export { cube, foo, graph };

// You should use this script in html with the type module.
// For example:
//   <script type="module" src="./demo.js"></script>
//
// Open the page in a http server, otherwise there will be a CORS policy error.
//
// script demo.js

import { cube, foo, graph } from "my-module";
graph.options = {
  color: "blue",
  thickness: "3px",
};
graph.draw();
console.log(cube(3)); // 27
console.log(foo); // 4.555806215962888

// module "my-module.js"
export default function cube(x) {
  return x * x * x;
}

import cube from "./my-module.js";
console.log(cube(3)); // 27