Examples of secondary encapsulation jquery ajax method (graphic tutorial)

The full name of Ajax is Asynchronous JavaScript and XML. The following article mainly introduces you to examples of secondary encapsulation of jquery ajax. The article introduces it in detail through sample code. Friends who need it can follow it. Let’s take a look.

Preface

The full name of Ajax is Asynchronous JavaScript and XML Asynchronous javaScript and XML

AJax involves Obtained technology:

1. Use CSS and XHTML to express.

2. Use DOM model for interaction and dynamic display.

3. Use XMLHttpRequest to communicate asynchronously with the server. (Core)

4. Use javascript to bind and call.

When our front-end processes data, it is inevitable to communicate with ajax and the background. Ajax communicates with the server through the XMLHttpRequest object. jquery encapsulates the $.ajax method on the basis of XMLHttpRequest. Communication, $.ajax method is very practical and very simple to use. This second encapsulation of query ajax, refer to express to add middleware to process data, return Promise (Defferd) objects, reduce callbacks, and write ajax more concisely and elegantly.

$.ajax({
 url: url,
 data: data,
 dataType: 'json',
 type: 'get',
 success: new Function(){},
 error: new Function(){},
 .......
})

Most of the time we only need to pass in the url and data to get the data we want.

Pain Points

But when using $.ajax in the project, it still has some pain points

The data returned by ajax for basically all projects is now encapsulated twice, and the information in the background when processing business logic is added.

From returning data, it becomes {code: 200, data:{}, err_msg:''｝

If every ajax request comes back, the code must be judged Whether it is correct before processing the business logic or reporting an error reminder, the entire project is too redundant.

$.ajax({
 url: url,
 data: data,
 success: function(data){
 if(data.code == 200) {
  dosomething()
 } else {
 alert(data.err_msg);
 }
 }
})

In order to solve this problem, we use a function to encapsulate $.ajax again, and put this This kind of correctness judgment is then processed and the business logic or error reminder is extracted and made into a public part.

util.ajax = function(obj, successFn){
 $.ajax({
 url: obj.url || '/interface',
 data: obj.data || {},
 dataType: obj.dataType || 'json',
 type: obj.type || 'get',
 success: function(data){
  if (data.code != 200) {
  alert(data.err_msg);
  } else {
  successFn(data.data)
  }
 },
 error: function(err){
  alert(err)
 }
 })
}

promise

Use util.ajax instead of $.ajax to reduce the It’s a wrong business judgment. Let's improve it again, instead of using callbacks, use promises to call, reducing callbacks and making the code clearer.

util.ajax = function(obj) {
 var deferred = $.Deferred();
 $.ajax({
  url: obj.url || '/interface',
  data: obj.data || {},
  dataType: obj.dataType || 'json',
  type: obj.type || 'get',
 }).success(function (data) {
  if (data.code != 200) {
   deferred.reject(data.err_msg);
  } else {
   deferred.resolve(data.data)
  }
 }).error(function (err) {
  deferred.reject('接口出错，请重试');
 })
 return deferred.fail(function (err) {
  alert(err)
 });
}


// 调用
var obj = {
 url: '/interface',
 data: {
  interface_name: 'name',
  interface_params: JSON.stringify({})
 }
};
util.ajax(obj)
 .done(function(data){
  dosomething(data)
 })

Middleware

This is a common method, but sometimes we need to deal with differentiation, we refer to express to introduce a middleware software to solve the differentiation problem.

util.ajax = function(obj, middleware) {
 var deferred = $.Deferred();
 $.ajax({
  url: obj.url || '/interface',
  data: obj.data || {},
  dataType: obj.dataType || 'json',
  type: obj.type || 'get',
 }).success(function (data) {
  if (data.code != 200) {
   deferred.reject(data.err_msg);
  } else {
   deferred.resolve(data.data)
  }
 }).error(function (err) {
  deferred.reject('接口出错，请重试');
 })

 // 添加中间件
 if(!middleware) {
  middleware = function(){};
 }
 return deferred.done(middleware).fail(function (err) {
  message({
   content: err,
   type: 'error',
   showLeftIcon: true,
   duration: 5000
  });
 });
}

// 调用
// 调用
var obj = {
 url: '/interface',
 data: {
  interface_name: 'name',
  interface_params: JSON.stringify({})
 }
};
var middleware = function(data) {
 data.forEach(function(item){
  item.fullName = item.firstName + item.lastName
 })
}
util.ajax(obj, middleware)
 .done(function(data){
  console.log(data.fullName)
 })

The above is what I compiled for everyone. I hope it will be helpful to everyone in the future.

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