Detailed explanation of data parameter type examples of JQuery.Ajax()_jquery

Suppose there is such a form now, which is used to add elements.

<form id='addForm' action='UserAdd.action' type='post'>
   <label for='uname'>用户名</label>：<input type='text' name='uname' id='uname'><br>
   <label for='mobileIpt'>手机号：</label><input type='text' name='mobileIpt' id='mobileIpt'><br>
   <label for='birthday'>生日：</label><input type='text' name='birthday'><br>
   <input type='button' value='提交' onclick='addUser()'>
</form>

We don’t want to use form submit to add this element, we want to use ajax to submit.

This is how we implemented it before:

function addUser(){
    var user = {
      uname:$("#uname").val(),
      mobileIpt:$("#mobileIpt").val(),
      birthday:$("#birthday").val()
    };
    $.ajax({
      url:'UserAdd.action',
      data:user,
      type:'post',
      dataType:'text',
      success:function(msg){
        if(msg=='1'){
          console.log('添加成功');
        }else{
          console.log('添加失败')
        }
      }
    })
  }

There is nothing wrong with this, but it is too troublesome to get the values ​​of form elements.... There are only three items here, and it will be useless if there are many items....

Until one day, I discovered jquery’s serializeArray method

Serialized table elements (similar to '.serialize()' method) return JSON data structure data.
Note that this method returns a JSON object rather than a JSON string. You need to use a plug-in or third-party library for stringification operations.
The returned JSON object consists of an array of objects, each of which contains one or two name-value pairs - the name parameter and the value parameter (if value is not empty).

Let’s give it a try

$('#addForm').serializeArray();
//返回数据结构，是json数组，每个对像分别name和value为key，代表这个表单元素的name和value
[
  {"name":"uname","value":""},
  {"name":"mobileIpt","value":""},  
  {"name":"birthday","value":""}
]

This seems to be useless

Let’s use the JQuery.param() method to handle it:

var arr = $('#addForm').serializeArray();
$.param(arr);
"uname=alice&mobileIpt=110&birthday=1983-05-12"

Hey, now it meets our needs. Although it is not of json type, it can at least be uploaded as data.

Here we can directly fill in the json array in the ajax data, and call $.param() inside jquery to process it.

Let’s take a look at the description of the jquery.param() method:

返回值:StringjQuery.param(obj,[traditional])
将表单元素数组或者对象序列化。
参数
obj,[traditional]
数组或jQuery对象会按照name/value对进行序列化，普通对象按照key/value对进行序列化。
traditional:是否使用传统的方式浅层序列化。
demo:
$.param({uanme:'vic',mobileIpt:'110',birthday:'2013-11-11'});
"uanme=vic&mobileIpt=110&birthday=2013-11-11"

Looking at the description, it seems that it has nothing to do with us. Let’s change it to a json array

$.param([{uanme:'vic'},{mobileIpt:'110'},{birthday:'2013-11-11'}]);
"undefined=&undefined=&undefined="

Is this conversion unsuccessful? Why can the data in our form be successfully converted into url parameters? Let’s take a look at the jquery source code

//在ajax()方法中，对json类型的数据进行了$.param()处理
if ( s.data && s.processData && typeof s.data !== "string" ) {
  s.data = jQuery.param( s.data, s.traditional );
}
//param方法中
if ( jQuery.isArray( a ) || ( a.jquery && !jQuery.isPlainObject( a ) ) ) {
    // Serialize the form elements
    jQuery.each( a, function() {
      add( this.name, this.value );
    });
  } else {
    // If traditional, encode the "old" way (the way 1.3.2 or older
    // did it), otherwise encode params recursively.
    for ( prefix in a ) {
      buildParams( prefix, a[ prefix ], traditional, add );
    }
  }

Now you understand, if it is json data, then loop one by one and only take their name attribute and value attribute to splice the string.

If it is a normal object, loop the properties of the object and then concatenate the strings.

Summary:

So, what this article is going to say is that in jquery’s ajax function, 3 types of data can be passed in

1. Text: "uname=alice&mobileIpt=110&birthday=1983-05-12"

2.json object: {uanme:'vic',mobileIpt:'110',birthday:'2013-11-11'}

3.json array:

[
  {"name":"uname","value":"alice"},
  {"name":"mobileIpt","value":"110"},  
  {"name":"birthday","value":"2012-11-11"}
]

So, we can get the form and submit it with one click, which is very convenient.

Supplement:

In fact, to extract form data, you only need to use the serialize() method to directly obtain "uname=alice&mobileIpt=110&birthday=1983-05-12".

ps: Summary of usage of data parameter of ajax method in jquery

$.ajax({
  type: post,
  url: some.php,
  data: name=john&location=boston, //第一种方式传参
 // data: {name:john,location:boston} //第二种方式传参
 // data: {foo:[bar1, bar2]} 转换为 '&foo=bar1&foo=bar2'
 /*
 第一种我们用url传参，参数里面如果加带&这个符号地话，可能参数接收不到或不完整，
 如“ data: name=john&location=boston,” 如果name地值是john&smith这样写可能就会有问题，
 我们可以用js里面地encodeuricomponent()方法进行转义，
 但如果用data: {name:john,location:boston}这种方式写地话就不需要进行转义，
 如果转义地话，接收地将是转义后地字符串
 */
  success: function(msg){
   alert( data saved: + msg );
  }
});