前言
答案我就不写了，各位大佬可以在浏览器中运行查看执行结果。也可以评论区留言，交流一下遇到的奇葩面试题。
1.
class Person{
constructor(age, name) {
this.age = age
this.name = name
}
}
let a1 = new Person(21, 'test')
let a2 = Person(22, 'wang')
console.log(a1)
console.log(a2)
// A. Person { age: 21, name: 'test' } TypeError:
// B. Person { age: 21, name: 'test' } Person { age: 22, name: 'wang' }
2.
class Person{
constructor(age, name) {
this.age = age
this.name = name
this.getX = () => {
return this.age * 1
}
}
getX() {
return this.age * 2
}
}
let a1 = new Person(5, 'test')
Person.prototype.getX = function() {
return this.age * 3
}
console.log(a1.getX())
// A. 5
// B. 10
// C. 15
// D. Error
class Person{
constructor(age, name) {
this.age = age
this.name = name
}
getX() {
return this.age * 2
}
}
let a1 = new Person(5, 'test')
Person.prototype.getX = function() {
return this.age * 3
}
console.log(a1.getX())
// A. 5
// B. 10
// C. 15
// D. Error
3.
class Animal {
speak() {
return this;
}
static eat() {
return this;
}
}
let obj = new Animal();
obj.speak();
let speak = obj.speak;
console.log(speak());
Animal.eat()
let eat = Animal.eat;
console.log(eat());
// A. undefined Animal {}
// B. undefined undefined
// C. Animal {} Animal {}
// D. Animal {} undefined
4.
const a = true, b = '2', c = 3
console.log(a + c - b)
console.log(a + b - c)
// A. 2 NaN
// B. true1 true-1
// C. 2 -1
// D. true1 -1
5.
const a = Promise.resolve('resolve1')
async function test(){
return await a
}
console.log(test())
// A. Promise { <pending> }
// B. Promise { 'resolve1' }
// C. Promise {}
6.
Promise.reject("error")
.catch((error) => console.log(error))
.then((error) => console.log(error));
// A. error error
// B. error undefined
// C. error
7.
for(let i = 0; i < 3; i++) {
let i = 'test'
console.log(i)
}
// 结果为：
8.
let a = 1
let a = 2
console.log(a)
// 结果为：
9.
<form class="file" data="file">
<input id="file" name="file">
</form>
A. document.querySelectorAll('file')[0]
B. document.getElementById('#file')
C. document.getElementsByTagName('file')[0]
D. document.querySelector('#file')
10.
function test() {
try {
throw 'error'
return 1
} finally {
return 2
}
}
console.log(test())
// A. 1
// B. 2
// C. error
// D. Error:...
11.
var a = 2, b
(function() {
console.log(a)
console.log(b)
var a = b = 5
console.log(a)
console.log(b)
})()
console.log(a)
console.log(b)
// 结果为：
12.
const a = {1: '1', 2: '2', 3: { 4: '4', 5: { 6: '6' }}}
const b = JSON.stringify(a)
JSON.parse(b, function(k, v){
console.log(k)
return v
})
// 结果为：
13.
console.log(1 || 2 && 3)
console.log(1 && 2 || 3)
console.log(1 && 2 && 3)
// 结果为：
14.
function foo() {
function bar() {
console.trace();
}
bar();
}
foo();
// 结果为：
15.
typeof console
typeof console.log
typeof console.log(a = 1)
typeof typeof console.log(a = 1)
// 结果为：
16.
['1','2','3'].map(parseInt)
// A. [ 1, 2, 3 ]
// B. TypeError:...
// C. [ NaN, NaN, NaN ]
// D. [ 1, NaN, NaN ]
17.
let map = new Map()
map.set(1, 1)
map.set(3, 3)
map.set(2, 2)
for(let v in map) {
console.log(v) // 结果为：
}
for(let v of map) {
console.log(v) // 结果为：
}
18. Set
let set = new Set()
set.add(1)
set.add(3)
set.add(2)
set.add(3)
for(let v in set) {
console.log(v) // 结果为：
}
for(let v of set) {
console.log(v) // 结果为：
}
19. 引用传递
let info = { a: 1 }
function test(info) {
let b = info.a
b = 2
}
test(info)
console.log(info.a)
let info = { a: 1 }
function test(info) {
let b = {}
b.a = info.a
b.a = 2
}
test(info)
console.log(info.a)
