JS題の印刷結果

var a = 1

function Fn1() {
    var a = 2
    alert(this.a + a)
}

function Fn2() {
    var a = 10
    Fn1()
}

Fn2() // 3 --- this.a  window   ；a           

var Fn3 = function() {
    this.a = 3
}

Fn3.prototype = {
    a: 4
}

var fn3 = new Fn3()

Fn1.call(fn3) // 5 --- fn3   {a: 3}，this.a      ，       ；a           

console.log(num)
function num() {} // f num()

console.log(num)
var num // undefined

(function(num) {
    console.log(num)
    function num() {}
})(100) // f num()

(function(num) {
    console.log(num)
    var num
})(100) // 100

var num = 100
var foo = {
    num: 200,
    bar: {
        num: 300,
        print: function() {
            console.log(this.num);
        }
    }
}
foo.bar.print()  // 300
let f = foo.bar.print
f() // 100
foo.bar.print.bind(foo)() // 200