How to judge json in JavaScript summarize _javascript techniques

Simply put, JSON converts a set of data represented in a JavaScript object to a string (pseudo object), which can then be easily passed between functions, or pass a string from a WEB client to a server-side program in an asynchronous application. This string looks a little odd (see some examples later), but JavaScript is easy to explain, and JSON can represent a more complex structure than name/value pairs. For example, you can represent arrays and complex objects, not just simple lists of keys and values.

To determine if JSON is empty

Copy Code code as follows:

var jsonstr ={};

1, to determine whether the JSON is empty

Copy Code code as follows:

Jquery.isemptyobject ();

2, determine whether the object is empty:

Copy Code code as follows:

if (typeOf (x) = = "undefined")
if (typeOf (x)!= "Object")
if (!x)

The third is the simplest method, but the third one cannot be judged by a mutually exclusive method of if (x), only in front of the object.

3, JSON key can not be repeated;

Copy Code code as follows:

jsonstr[key]= "XXX"

exists in the substitution, does not exist is added.

4. Traverse JSON

for (var key in jsonstr) {

  alert (key+ "+jsonstr[key])

}
Isjson = function (obj) {
  var Isjson = typeof (obj) = = "Object" && Object.prototype.toString.call (obj). toLowerCase () = = "[Object Object]" &&!obj.length;< C5/>return Isjson;
}
if (!isjson (data)) data = eval (' (' +data+ ') ');//convert string to JSON format

Structure in JSON: objects and arrays.

1. The object

An object ends with "{" Beginning, "}". Each "key" is followed by a ":", "Key/value" to "use", "separated."

Copy Code code as follows:

Packjson = {"Name": "Nikita", "Password": "1111"}

2. Array

Copy Code code as follows:

Packjson = [{"Name": "Nikita", "Password": "1111"}, {"Name": "Tony", "Password": "2222"}];

An array is an ordered collection of values. An array ends with "[" Beginning, "]". Values are separated by ",".

The above is the introduction of JS JSON in the judgment method, I hope you like.