ajax json parameter data in the object using the difference between the string json

Reprinted: https: //blog.csdn.net/u011280342/article/details/79789379

There is a data parameter in the jquery ajax which is the data to the server of the customer 
we look at the first common wording:

A  front-end code:
 2    var username = $ ( '# phone_email_num' ) .val ();
 . 3    var pwd = $ ( '# password' ) .val ();
 . 4    $ .ajax ({
 . 5           URL: 'the login.php' ,
 . 6           type: 'POST' ,
 . 7           Data: {username: username, pwd: pwd},   // this is the object json 
. 8           Success: function (Data)} {......
 . 9     )};
 10  
. 11  backend Code:
 12  we print values over post
 13 is  the dump ($ _ the pOST);
 14  results:
 15  the Array
 16  (
 . 17     [username] => 18711111111
18     [pwd] => 123456
19 )

We look at the second writing:

Front-end code 
$ .ajax ({ 
       URL: 'the login.php' , 
       type: 'POST' , 
       Data: the JSON.stringify ({A: 'A', B: 'B'}), // this is json string 
       contentType : 'file application / JSON',   // predetermined value is passed JSON 
       Success: function (Data) {...} 
)}; 

back-end code: 
this time the dump ($ _ POST); result: 
the Array 
( 
) 
nothing , we can use the following method: 
$ _POST = of json_decode (file_get_contents ( 'PHP: // INPUT'), to true ); 
then dump ($ _ POST); result: 
the Array 
( 
    [A] => A 
    [B] => b
)

ajax first case of default is application / x-www-form-urlencoded submission. That is the common form submission. Use $ _POST way in PHP can easily get, if you use an ajax application / json way, remember that data argument is a string type. Use JSON.stringify () to change my

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