Import Export

// addition.js
function addTwo(a,b){
    return a + b;
}
export { addTwo };

// app.js
import { addTwo } from './addition';
console.log(addTwo(2, 4)); // 6

import/export multiple

// addition.js
function addTwo(a,b){
    return a + b;
}

function addThree(a,b,c){
    return a + b + c;
}

export { addTwo, addThree };

// app.js
import { addTwo, addThree } from './addition';

console.log(addTwo(2, 4)); // 6
console.log(addThree(2, 4, 5)); // 11

export other variation

// addition.js
export function addTwo(a,b){
    return a + b;
}

export function addThree(a,b,c){
    return a + b + c;
}

Rename exported function - addTwo as addTwoNumber

// addition.js
function addTwo(a,b){
    return a + b;
}

function addThree(a,b,c){
    return a + b + c;
}

export { addTwo, addThree };

// app.js
import { addTwo as addTwoNumber, addThree } from './addition';
console.log(addTwoNumber(6, 4)); // 10
console.log(addThree(2, 4, 5)); // 11

import all in one shot

// app.js
import * as adder from './addition';
console.log(adder.addTwoNumber(6, 4)); // 10
console.log(adder.addThree(2, 4, 5)); // 11

Use case ( with lodash )

// users.js
export var users = [
    {name: "hemant", age: 20, location: "hyderabad"},
    {name: "vinay", age: 80, location: "hyderabad"},
    {name: "paa", age: 90, location: "hyderabad"},
    {name: "varun", age: 44, location: "hyderabad"}
];

// app.js
import * as _ from "lodash"; // npm i lodash -S
import {users } from './users';

console.log(_.where(users, {age: 20}));