【前端面试】前端面试题300道~~熬夜吐血整理，2024年最新大厂面试经验分享稿

flightHandler({
“code”: “CA1998”,
“price”: 1780,
“tickets”: 5
});

class Node{
Node next=null;
int data;
public Node(int data){
this.data=data;
}
}
public class MyLinkedList {
Node head=null;//链表头的引用
public Node findElem(Node head,int k){
if(k<1||k>this.length()){
return null;
}
Node p1=head;
Node p2=head;
for(int i=0;i
p1=p1.next;
while(p1!=null){
p1=p1.next;
p2=p2.next;
}
return p2;
}
public static void main(String[] args) {
MyLinkedList list=new MyLinkedList();
list.addNode(1);
list.addNode(2);
list.addNode(3);
list.addNode(4);
list.addNode(5);
MyLinkedList p=new MyLinkedList();
p.head=list.findElem(list.head, 3);
p.printList();
}
}

GET /hello.txt HTTP/1.1
User-Agent: curl/7.16.3 libcurl/7.16.3 OpenSSL/0.9.7l zlib/1.2.3
Host: www.example.com
Accept-Language: en, mi
服务端响应:
HTTP/1.1 200 OK
Date: Mon, 27 Jul 2009 12:28:53 GMT
Server: Apache
Last-Modified: Wed, 22 Jul 2009 19:15:56 GMT
ETag: “34aa387-d-1568eb00”
Accept-Ranges: bytes
Content-Length: 51
Vary: Accept-Encoding
Content-Type: text/plain
输出结果：
Hello World! My payload includes a trailing CRLF.

var person = function(){
//变量作用域为函数内部，外部无法访问
var name = “default”;
return {
getName : function(){
return name;
},
setName : function(newName){
name = newName;
}
}
}();
print(person.name);//直接访问，结果为undefined
print(person.getName());
person.setName(“a”);
print(person.getName());
//得到结果如下：
undefined
default
a

#div1{
width: 100px;
display: inline-block;
background-color: black;
}
#div2{
display: inline-block;
position: absolute;
left: 100px;
right: 0px;
background-color: red;
}

$.extend({
hello:function(){alert(‘hello’);}
});
2、$.fn.extend(src)
该方法将src合并到jquery的实例对象中去，如:
$.fn.extend({
hello:function(){alert(‘hello’);}
});

attr(key,value)
$(“#myphoto”).attr(“src”,“/pic/1.jpg”);

function fact(num) {
if (num <= 1) {
return 1;
} else {
return num * fact(num - 1);
}
}
以下代码可导致出错：
var anotherFact = fact;
fact = null;
alert(antherFact(4)); //出错
由于fact已经不是函数了，所以出错。
用arguments.callee可解决问题，这是一个指向正在执行的函数的指针,arguments.callee返回正在被执行的对现象。
新的函数为：
function fact(num) {
if (num <= 1) {
return 1;
} else {
return num * arguments.callee(num - 1); //此处更改了。
}
}
var anotherFact = fact;
fact = null;
alert(antherFact(4)); //结果为24.

function getJson(url){
return new Promise((resolve, reject) =>{
var xhr = new XMLHttpRequest();
xhr.open(‘open’, url, true);
xhr.onreadystatechange = function(){
if(this.readyState == 4){
if(this.status = 200){
resolve(this.responseText, this)
}else{
var resJson = { code: this.status, response: this.response }
reject(resJson, this)
}
}
}
xhr.send()
})
}
function postJSON(url, data) {
return new Promise( (resolve, reject) => {
var xhr = new XMLHttpRequest()
xhr.open(“POST”, url, true)
xhr.setRequestHeader(“Content-type”, “application/x-www-form-urlencoded”);
xhr.onreadystatechange = function () {
if (this.readyState === 4) {
if (this.status === 200) {
resolve(JSON.parse(this.responseText), this)
} else {
var resJson = { code: this.status, response: this.response }
reject(resJson, this)
}
}
}
xhr.send(JSON.stringify(data))
})
}
getJSON(‘/api/v1/xxx’) // => 这里面是就try
.catch( error => {
// dosomething // => 这里就是catch到了error，如果处理error以及返还合适的值
})
.then( value => {
// dosomething // 这里就是final
})

function Parent(){
this.name = “parent”;
}
Parent.prototype.getName = function(){
return this.name;
}
function Child(){
this.name = “child”;
}
//继承parent
Child.prototype = new Parent();
2.构造函数继承
function Animal(name){
this.name = name;
this.eat = function(){
consoel.log(this.name + “吃饭”);
}
}
var cat = new Animal(“maomi”);
cat.name;
cat.eat();

function deepCopy(obj){
//判断是否是简单数据类型，
if(typeof obj == “object”){
//复杂数据类型
var result = obj.constructor == Array ? [] : {};
for(let i in obj){
result[i] = typeof obj[i] == “object” ? deepCopy(obj[i]) : obj[i];
}
}else {
//简单数据类型 直接 == 赋值
var result = obj;
}
return result;
}

<1>.长度为n(n>1),把该输入序列分成两个长度为n/2的子序列；
<2>.对这两个子序列分别采用归并排序，直到长度n小于2；
<3>.将两个排序好的子序列合并成一个最终的排序序列。
function mergeSort(arr) {
var len = arr.length;
if(len < 2) {
return arr;
} else {
middle = Math.floor(len / 2);
var left = arr.slice(0, middle);
var right = arr.splice(middle);
return merge(mergeSort(left), mergeSort(right));
}
}
function merge(left, right) {
var result = [];
while(left.length && right.length) {
left[0] > right[0] ? result.push(right.shift()): result.push(left.shift());
}
if(left.length) {
result = result.concat(left);
}
if(right.length) {
result = result.concat(right);
}
return result;
}

var ajax = {};
ajax.x = function () {
if (typeof XMLHttpRequest !== ‘undefined’) {
return new XMLHttpRequest();
}
var versions = [
“MSXML2.XmlHttp.6.0”,
“MSXML2.XmlHttp.5.0”,
“MSXML2.XmlHttp.4.0”,
“MSXML2.XmlHttp.3.0”,
“MSXML2.XmlHttp.2.0”,
“Microsoft.XmlHttp”
];
var xhr;
for (var i = 0; i < versions.length; i++) {
try {
xhr = new ActiveXObject(versions[i]);
break;
} catch (e) {
}
}
return xhr;
};
ajax.send = function (url, method, data, success,fail,async) {
if (async === undefined) {
async = true;
}
var x = ajax.x();
x.open(method, url, async);
x.onreadystatechange = function () {
if (x.readyState == 4) {
var status = x.status;
if (status >= 200 && status < 300) {
success && success(x.responseText,x.responseXML)
} else {
fail && fail(status);
}
}
};
if (method == ‘POST’) {
x.setRequestHeader(‘Content-type’, ‘application/x-www-form-urlencoded’);
}
x.send(data)
};
ajax.get = function (url, data, callback, fail, async) {
var query = [];
for (var key in data) {
query.push(encodeURIComponent(key) + ‘=’ + encodeURIComponent(data[key]));
}
ajax.send(url + (query.length ? ‘?’ + query.join(‘&’) : ‘’), ‘GET’, null, success, fail, async)
};
ajax.post = function (url, data, callback, fail, async) {
var query = [];
for (var key in data) {
query.push(encodeURIComponent(key) + ‘=’ + encodeURIComponent(data[key]));
}
ajax.send(url,‘POST’, query.join(‘&’), success, fail, async)
};
使用方法：GET
ajax.get(‘/test.php’, {foo: ‘bar’}, function(response,xml) {
//success
},
function(status){
//fail
});
POST
ajax.post(‘/test.php’, {foo: ‘bar’}, function(response,xml) {
//succcess
},function(status){
//fail
});