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October 10th, 2018 ×

Top 18 New Things in JS - Part 2

Wes Bos

Wes Bos Host

Scott Tolinski

Scott Tolinski Host

or
Show Notes Transcript

In this episode Wes and Scott continue the discussion of their favorite top 18 new things in Javascript.

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Show Notes

3:30

  • Spread
const array1 = [1, 2, 3]
const array2 = [0, ...array1]

8:40

  • Rests
const teams = [player1, player2, player3]
const [leader, ...members] = teams

11:54

  • Arrow Functions
const add = (x, y) => {
  return x + y
}
// equal to
const add = (x, y) => x + y

15:48

  • Default Function Arguments
function mul(x, y = 1) {
  return x * y
}
mul(2, 3) // 2 * 3 = 6
mul(2) // 2 * 1 = 2

19:47

  • Named params
function ({ array, element }) {
  return [element, ...array]
}

21:26

  • Modules
// @ a.js
export const param = 1
const defaultParam = 2
export default defaultParam

// @ b.js
import defaultParam, { param } from './a'

// rename import module
import newDefaultParam from './a' // rename default export directly
import { param as newParam} from './a' // use `as` for rename

35:35

  • Classes
class Polygon {
  constructor(height, width) {
    this.height = height;
    this.width = width;
  }

  get area() {
    return this.calcArea();
  }
  
  calcArea() {
    return this.height * this.width;
  }
}

class Square extends Polygon {
  ...
}

41:54

  • Things we never use
await const users = fetchUser().catch(e => ...)

for(let element of array) { ... }

const set1 = new Set([1, 2, 3, 4, 5]);

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