es6/es7/typescript

[changtimwu]

• using async/awaint in babel: http://masnun.com/2015/11/11/using-es7-asyncawait-today-with-babel.html
• syntax highlight https://github.com/othree/es.next.syntax.vim

" for ES6
Plugin 'othree/yajs.vim'
" for ES7
Plugin 'othree/es.next.syntax.vim'

• typescript 1.7 also supports async/await http://blogs.msdn.com/b/typescript/archive/2015/11/30/announcing-typescript-1-7.aspx

[changtimwu]

async syntax comparison

babel

require("babel-polyfill");

import request from "request";
async function main() {
  await pingmany();
}

async function pingmany() {
  for (var i = 0; i < 10; i++) {
    await delay(1000);
    console.log("ping");
  }
}

function delay(ms) {
  return new Promise(resolve => setTimeout(resolve, ms));
}
main();

typescript 1.7

async function main() {
  await pingmany();
}

async function pingmany() {
  for (var i = 0; i < 10; i++) {
    await delay(1000);
    console.log("ping");
  }
}

function delay(ms) {
   return new Promise(resolve => setTimeout(resolve, ms));
}

main();

almost identical but why ts doesn't need polyfill?

[changtimwu]

• 想要 call await 的 function, caller 本身必須有 async

function delay(ms) {
  return new Promise(resolve => setTimeout(resolve, ms));
}

async function caller() {
  //ok
  await delay();
}

//error!
await delay();

• 已經有 async 的 function, 用不用await 去call 沒差

[changtimwu]

please study the advance type to understand all variations. https://www.typescriptlang.org/docs/handbook/advanced-types.html

[changtimwu]

define type with infinite set of values

    type _quarter = "quarter" | "quarters" | "Q";
    type _isoWeek = "isoWeek" | "isoWeeks" | "W";
    type _date = "date" | "dates" | "D";
    type StartOf = Base | _quarter | _isoWeek | _date;
    startOf(unitOfTime: StartOf): Moment;

startOf( 'day') //ok
startOf('xday') // error

[changtimwu]

complicated typing cases

Traditional JS libs usually are used to have some

var BigNumber = require
var b1= new BigNumber(3) // it's a class, which is newable
var b2 = BigNumber.EUCLID // it also has static members

How to type this kind of lib inside a TS interface/class?

import BigNumber from 'bignumber.js'

interface fff {
   //BN:BigNumber //wrong this means BN is an instance of BigNumber
    BN:typeof BigNumber
}

function bfunc( b:fff){
  var gg= new b.BN(3) //ok! it's a 
  var rr = b.BigNumber.EUCLID  //ok! it's accessible 
}