jcreamer898

Type 'from' in the editor and...

jcreamer898

What even is TypeScript?

JavaScript + Types = Typescript

TypeScript as a compilter

npm i -g typescript

./node_modules/.bin/tsc

jcreamer898

#!/bin/sh

set -e

POSITIONAL=()
while [[ $# -gt 0 ]]
do
key="$1"

case $key in

jcreamer898

From a few tweetstorms by https://www.twitter.com/a_robson...

https://twitter.com/A_Robson/status/959838117619556352 https://twitter.com/A_Robson/status/960195581846147072

jcreamer898

import * as React from "react";
import formatPrice from "../utils/formatPrice";

export interface IPriceProps {
  num: number;
  symbol: "$" | "€" | "£";
}

const Price: React.SFC<IPriceProps> = ({
  num,

jcreamer898

// @ts-check
/**
* Format a price
* @param num {number} The price
* @param symbol {string} The currency symbol
*/
const formatPrice = (num, symbol = "$") => 
  `${symbol}${num.toFixed(2)}`;

formatPrice("1234");

jcreamer898

const formatPrice = (num: number, symbol = "$": string) =>   
  `${symbol}${num.toFixed(2)}`; formatPrice("1234"); 
   // num.toFixed is not a function

jcreamer898

const formatPrice = (num, symbol = "$") =>
  `${symbol}${num.toFixed(2)}`; formatPrice("1234");

jcreamer898

{
  "version": "0.2.0",
  "configurations": [
    {
      "type": "node",
      "request": "launch",
      "name": "Run tests",
      "program": "${workspaceRoot}/node_modules/.bin/jest"
    },
    {

jcreamer898

Name of thing	Sorta like...	Mounted?	Can you even setState?	What would you say... ya do here?
constructor	initialize()	nope	nope	init stuff NO side effects
componentWillMount	beforeDomReady()	nope	yeah but don't	Only needed in createClass now use constructor for most things
render	render	nope	please no	render stuff and don't set any state please
componentDidMount	domReady()	yup	yup	DOM is a go init jQuery plugins dispatch stuff
componentWillReceiveProps	onChange()	yup	yup