1. 程式人生 > >面試題集錦;有關作用域和this的指向

面試題集錦;有關作用域和this的指向

作用域面試題:

1.

fn() function fn () { console.log(12) } var as = function () { console.log(45) }

2.

var a = 12; function fn () { console.log(a) var a = 45; console.log(a) } fn()

3.

var a = 12; function fn () { console.log(a) a = 45; console.log(a) } fn()

4.

function fn () { console.log(11) function ff () { console.log(22) } ff() } fn()

5.

function fn () { console.log(5) fn() } fn()

6.

function fn () { console.log(12) } var as = fn() console.log(as)

7.

function fn () { console.log(12); return 45; console.log(456) } var as = fn()

8.

var a = 12; function fn () { console.log(a); return 4; var a = 45; } fn()

 9.

var a = 45; function fn () { console.log(a) } fn()

10.

var a = 45; function fn (a) { console.log(a) } fn(5)

11.

var a = 123; function fun () { alert(a); } fun()

12.

var a = 123; function fun () { alert(a); var a = 456; } fun(); alert(a);

13.

var a = 123; function fun () { alert(a); a = 456; } fun() alert(a)

14.

var a = 123; function fun (a) { alert(a) a = 456; } fun() alert(a)

15.

var a = 123; function fun (a) { alert(a) a = 456 } fun() alert(a)  

16.

function makeNoSense (x) { this.x = x; } makeNoSense(5); console.log(x); function test () { this.x = 1; alert(this.x); } test();    

This的面試題

1.

var name = '222'; var a = { name : '111', say : function () { console.log(this.name) } }
var fun = a.say; fun() //??? a.say() //???
var b = { name : '333', say : function (fun) { fun(); } } b.say(a.say); //??? b.say = a.say; b.say() //???  

2.

var val = 1
var obj = {
val : 2,
dbl : function() {
var val = 45;
console.log(this); //指向誰?
this.val *= 2;
console.log(this.val); //??
console.log(val); //??
}
}
var fn = obj.dbl
fn()

 

 

3.

var x = 12;
function test() {
console.log(this.x)
}
test() //??

 

4.

var x = 12;
function test() {
console.log(this.x)
}
var obj={
x:45,
ss:test
}
obj.ss() //??

 

5.

var x = 12;
function test() {
console.log(this.x)
}
var obj = {
x:45,
ss:function(){
console.log(this)
test()
}
}
obj.ss() //??

 

6.

var val = 1
var obj = {
val : 2,
dbl : function() {
// var val = 45;
console.log(this); // 指向誰
this.val *= 2;
console.log(this.val); // ???
console.log(val); // ???
}
}
var ff = obj.dbl()