Exploring Javascript ES6 Features

Just putting together a bunch of ES6 features.

Arrow function

const foo = x => x;

const foo = (x, y) => x + y;

const foo = (x, y) => ({x, y, z: x + y});

const foo = (x, y) => { 
    const z = [x, y];
    // ...
    return z;
}

// Currying
const add = (x) => (y) => (z) => x + y + z;
const addFiveTo = add(2)(3);
addFiveTo(3); // 8

Default value

const foo = num ?? 1;

const foo = (x = 1) => x;

const options = (userOptions) => ({...defaultOptions, ...userOptions});

const foo = ({ x = 1, y = 2 }) => x + y

const { x, y, z = 3 } = { x: 1, y: 2 };

const [ x, y, z = 3 ] = [1, 2]

Spread operator / Destructuring

const arr = [1, 2, 3];

arr = [...arr, 4];

arr = [4, ...arr];

arr = [...arr, ...arr2];

const [ first, ...others ] = arr;

const { x, ...others } = { x: 1, y: 2, z: 3 };

const foo = (x, y, z) => x + y + z, arr = [1, 2, 3];
foo(...arr);

const { x, y } = foo;

const foo = { x, y };

const z = {
    x(){ foo(); },
    y()( bar(); }
}

Rest operator

const foo = (...args) => args.join('');

Template literals

// Multi-line
const foo = `this is one line,
another line`;

// Interpolation
const foo = `the value is ${x}`;

// Tagged templates
const foo = (str, column, table) => db.select(x).from(table);
foo`select ${x} from ${table}`;