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<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width">
    <meta name="description" content="箭頭函式">
    <title>箭頭函式</title>
  </head>
  <body>
    <section>綁定this</section>
  <script id="jsbin-javascript">
// ori
const obj = {
  a: 1
}

function func() {
  const that = this

  setTimeout(
    function() {
      console.log(that)
    }, 2000)
}

func.call(obj) //Object {a: 1

// arrow

function func() {
  setTimeout(
    () => {
      console.log(this)
    }, 2000)
}

// 用bind來回傳部分函式（partial function）的語法
function add(x, y){
  return x + y
}

function puls1Factory(y){
  return add(1,y)
}

const puls1Bind = add.bind(undefined, 1)

const puls1Arrrow = y => add(1,y)
</script>
</html>