Ajax usage of jQuery learning notes

He took my life 2021-01-22 01:17:17
ajax usage jquery learning notes


AJAX The advantages and disadvantages of

  • advantage 1. Modify the data without refreshing the page 2. asynchronous communication , Fast response 3. Jianqigong server burden
  • shortcoming 1. browser back invalid , Damage to browser return function 2. There are security risks 3. Poor support for search engines 4. No use URL Direct access

Common scenarios

  • Login registration data validation ( The user does not exist or already exists )
  • Drop down search DataTips
  • ......

Use native JS To write a AJAX Method

1. First , First, create a variable to store XMLHttpRequest object

var http = null;

2. establish XMLHttpRequest object

http = new XMLHttpRequest();

3. utilize open(...) Method to configure


open The method has three arguments , Namely
  • method ( Request mode )
  • url ( Request address )
  • async ( Asynchronous or not ) The first parameter sets its request mode , As is common GET and POST, The second parameter setting URL, It can be a background file path or a network address . The third is to ask if you need an asynchronous request , Here are some general suggestions true, After all ajax Its function is to obtain data asynchronously .
http.open('GET' , '/api/test.php?name=wang' , true);

If POST Submitted words , Then you need to set the request header , Set the parameter to sen(); in
http.open('POST','/api/test.php',true)http.setRequestHeder(xxxxx Format );http.send('name=wang');

4. adopt XMLHttpRequest,send() Submit

http.send();

5. Process the server response


After submitting the request , We can go through onreadystatechage To monitor the response , See if it works ,readyState There are five states , arrive 4 The corresponding content has been solved , It can also be done through XMLHttpRequest.onload Instead of , Be equal to 4 when , adopt status Get status code .
http.onload = function (){ if(http.status === 200){ console.log('ajax yes!'); }else{ console.log('ajax no!') }}

Details of status code


 Status code Information 200 Indicates that the response result request has been processed normally 204 Indicates that the resource request was successful , But there are no resources to return 206 Represents a part of the requested resource , The response contains content-range301 Represents the access path of the resource (URL) Changed 302 Indicates that the requested resource is already in another location , But by default you already know 303 Indicates that the requested resource is already in another location , You should use GET Method to get the requested resource .304 Indicates that the resource has been requested , But not in the normal way 307 Temporary redirection .400 Syntax error in request message , You need to modify the request content and re request 401 Need to pass through http authentication , If it has been done before 1 Requests , It means to use User authentication failed 403 The server denied your access 404 There are no requested resources on the server , Maybe the address is wrong .......405 The request method of the client is forbidden by the server 500 An error occurred with the server resource 503 The server was unable to request a summary 2xx For the request to succeed ,3xx by URL Has been changed ,4xx Client error ,5xx Server error 

encapsulation ajax Method

 /** /** * ajax encapsulation , Parameter passes an object * url : Request address * type : Request mode * dataType : Request value return value * data : Parameter object * async : asynchronous * success : function Success function => The parameter is the response content * error : function Exception function => The parameter content is the response code **/ var ajax = function (obj) { // By default, an object is passed in , without , It's an empty object obj = obj || {}; // Default GET request obj.type = (obj.type || 'GET').toUpperCase(); // Default return JSON data obj.dataType = obj.dataType || 'JSON'; // Default asynchronous request obj.async = obj.async || true; // Processing parameters , perform getParams Method var data = getParams(obj.data); var http; /** * establish AJAX Instance adaptation of * W3C Use XMLHttpRequest * IE Use ActiveXObject('Microsoft.XMLHTTP'); * */ if (window.XMLHttpRequest){ //w3c http = new XMLHttpRequest(); }else { //IE http = new ActiveXObject('Microsoft.XMLHTTP'); } /** * Encapsulation of request mode * GET and POST request * */ if (obj.type === 'GET'){ http.open("GET",obj.url+'?'+data,obj.async); http.send(); }else if (obj.type === 'POST'){ http.open('POST',obj.url,obj.async); // Set the head parameters http.setRequestHeader('Content-Type','application/x-www-form-urlencoded'); // Submit post data http.send(data); } /** * Listen response interface * If step 4 If the request status code of is correct, execute success function * If it's wrong, do it error function * */ http.onreadystatechange = function () { if (http.readyState === 4){ // If the response is complete , Judge status code var status = http.status; if (status >= 200 && status < 300){ // Callback obj.success && obj.success(http.responseText,http.responseXML); } else { obj.error && obj.error(status); } } }; }; /** * Object parameter processing * Convert to the desired string */ function getParams(data) { var arr = []; for (var param in data){ arr.push(encodeURIComponent(param) + '=' +encodeURIComponent(data[param])); } console.log(arr); arr.push(('randomNumber=' + Math.random()).replace('.')); return arr.join('&'); }

jQuery Of AJAX Encapsulation method

jQuery Packaged ajax Use GET

$.ajax({ type:'get', url: "url", data:{'foo':'bar'}, success: function(res) { load_content(res); }}); 

POST
$.ajax({ url: "url", success: function(res) { // Set it on the page console.log(typeof res); }});

jquery Of ajax The principle is relatively similar , It deals with a lot of compatibility issues for developers , Greatly optimized the developer in writing ajax Cause code duplication ...
版权声明
本文为[He took my life]所创,转载请带上原文链接,感谢
https://javamana.com/2021/01/20210122011422367w.html

  1. 【计算机网络 12(1),尚学堂马士兵Java视频教程
  2. 【程序猿历程,史上最全的Java面试题集锦在这里
  3. 【程序猿历程(1),Javaweb视频教程百度云
  4. Notes on MySQL 45 lectures (1-7)
  5. [computer network 12 (1), Shang Xuetang Ma soldier java video tutorial
  6. The most complete collection of Java interview questions in history is here
  7. [process of program ape (1), JavaWeb video tutorial, baidu cloud
  8. Notes on MySQL 45 lectures (1-7)
  9. 精进 Spring Boot 03:Spring Boot 的配置文件和配置管理,以及用三种方式读取配置文件
  10. Refined spring boot 03: spring boot configuration files and configuration management, and reading configuration files in three ways
  11. 精进 Spring Boot 03:Spring Boot 的配置文件和配置管理,以及用三种方式读取配置文件
  12. Refined spring boot 03: spring boot configuration files and configuration management, and reading configuration files in three ways
  13. 【递归,Java传智播客笔记
  14. [recursion, Java intelligence podcast notes
  15. [adhere to painting for 386 days] the beginning of spring of 24 solar terms
  16. K8S系列第八篇(Service、EndPoints以及高可用kubeadm部署)
  17. K8s Series Part 8 (service, endpoints and high availability kubeadm deployment)
  18. 【重识 HTML (3),350道Java面试真题分享
  19. 【重识 HTML (2),Java并发编程必会的多线程你竟然还不会
  20. 【重识 HTML (1),二本Java小菜鸟4面字节跳动被秒成渣渣
  21. [re recognize HTML (3) and share 350 real Java interview questions
  22. [re recognize HTML (2). Multithreading is a must for Java Concurrent Programming. How dare you not
  23. [re recognize HTML (1), two Java rookies' 4-sided bytes beat and become slag in seconds
  24. 造轮子系列之RPC 1:如何从零开始开发RPC框架
  25. RPC 1: how to develop RPC framework from scratch
  26. 造轮子系列之RPC 1:如何从零开始开发RPC框架
  27. RPC 1: how to develop RPC framework from scratch
  28. 一次性捋清楚吧,对乱糟糟的,Spring事务扩展机制
  29. 一文彻底弄懂如何选择抽象类还是接口,连续四年百度Java岗必问面试题
  30. Redis常用命令
  31. 一双拖鞋引发的血案,狂神说Java系列笔记
  32. 一、mysql基础安装
  33. 一位程序员的独白:尽管我一生坎坷,Java框架面试基础
  34. Clear it all at once. For the messy, spring transaction extension mechanism
  35. A thorough understanding of how to choose abstract classes or interfaces, baidu Java post must ask interview questions for four consecutive years
  36. Redis common commands
  37. A pair of slippers triggered the murder, crazy God said java series notes
  38. 1、 MySQL basic installation
  39. Monologue of a programmer: despite my ups and downs in my life, Java framework is the foundation of interview
  40. 【大厂面试】三面三问Spring循环依赖,请一定要把这篇看完(建议收藏)
  41. 一线互联网企业中,springboot入门项目
  42. 一篇文带你入门SSM框架Spring开发,帮你快速拿Offer
  43. 【面试资料】Java全集、微服务、大数据、数据结构与算法、机器学习知识最全总结,283页pdf
  44. 【leetcode刷题】24.数组中重复的数字——Java版
  45. 【leetcode刷题】23.对称二叉树——Java版
  46. 【leetcode刷题】22.二叉树的中序遍历——Java版
  47. 【leetcode刷题】21.三数之和——Java版
  48. 【leetcode刷题】20.最长回文子串——Java版
  49. 【leetcode刷题】19.回文链表——Java版
  50. 【leetcode刷题】18.反转链表——Java版
  51. 【leetcode刷题】17.相交链表——Java&python版
  52. 【leetcode刷题】16.环形链表——Java版
  53. 【leetcode刷题】15.汉明距离——Java版
  54. 【leetcode刷题】14.找到所有数组中消失的数字——Java版
  55. 【leetcode刷题】13.比特位计数——Java版
  56. oracle控制用户权限命令
  57. 三年Java开发,继阿里,鲁班二期Java架构师
  58. Oracle必须要启动的服务
  59. 万字长文!深入剖析HashMap,Java基础笔试题大全带答案
  60. 一问Kafka就心慌?我却凭着这份,图灵学院vip课程百度云