What are json and jsonp, jQuery json examples are explained in detail_json

What is JSON?
As briefly mentioned before, JSON is a text-based data exchange method, or a data description format. Whether you should choose it must first pay attention to its advantages.

Advantages of JSON:
1. Based on plain text, cross-platform transmission is extremely simple;
2. Javascript is natively supported, and almost all background languages ​​are supported;
3 , lightweight data format, occupying very few characters, especially suitable for Internet transmission;
4. Strong readability, although not as clear as XML, but it is still easy to identify after reasonable indentation. ;
5. Easy to write and parse, of course, provided you know the data structure;
JSON certainly has shortcomings, but in the author's opinion they are really insignificant, so they will not be explained separately.

JSON format or rules :
JSON can describe the data structure in a very simple way. It can do everything XML can do, so both are cross-platform. Completely indistinguishable.
1. JSON has only two data type descriptors, curly brackets {} and square brackets []. The remaining English colons: are mapping characters, English commas are delimiters, and English double quotes "" are defining characters.
2. Curly brackets {} are used to describe a set of "different types of unordered key-value pair sets" (each key-value pair can be understood as an OOP attribute description), and square brackets [] are used to describe a set of " "Ordered data collection of the same type" (which can correspond to OOP arrays).
3. If there are multiple sub-items in the above two sets, they should be separated by commas.
4. The key-value pairs are separated by English colon:, and it is recommended that the key names be added with English double quotes "" to facilitate the parsing of different languages.
5. Commonly used data types within JSON are nothing more than strings, numbers, Boolean, dates, and null. Strings must be enclosed in double quotes, and the rest are not used. The date type is quite special, so I won’t go into details here. Yes, I just suggest that if the client does not have the function of sorting by date, then just pass the date and time directly as a string, which can save a lot of trouble.
JSON instance:

Copy code The code is as follows:

// Describe a person
var person = {
"Name": "Bob",
"Age": 32,
"Company": "IBM",
"Engineer": true
}
// Get this person’s information
var personAge = person.Age;
// Describe several people
var members = [
{
"Name" : "Bob",
"Age": 32,
"Company": "IBM",
"Engineer": true
},
{
"Name": " John",
"Age": 20,
"Company": "Oracle",
"Engineer": false
},
{
"Name": "Henry" ,
"Age": 45,
"Company": "Microsoft",
"Engineer": false
}
]
// Read John’s company name
var johnsCompany = members[1].Company;
//Describe a conference
var conference = {
"Conference": "Future Marketing",
"Date": "2012-6 -1",
"Address": "Beijing",
"Members":
[
{
"Name": "Bob",
"Age": 32,
"Company": "IBM",
"Engineer": true
},
{
"Name": "John",
"Age": 20,
"Company": "Oracle",
"Engineer": false
},
{
"Name": "Henry",
"Age": 45,
" Company": "Microsoft",
"Engineer": false
}
]
}
// Read whether the participant Henry is an engineer
var henryIsAnEngineer = conference.Members[ 2].Engineer;

What is JSONP?
In fact, there are many explanations about JSONP on the Internet, but they are all the same and vague. It is a bit difficult for many people who are new to it to understand. It is not a small thing, but I try to explain this problem in my own way. See if that helps.
1. A well-known problem, Ajax direct request for ordinary files has the problem of cross-domain unauthorized access. Regardless of whether you are a static page, dynamic web page, web service, or WCF, as long as it is a cross-domain request, it is not allowed;
2. However, we also found that when calling js files on a Web page, it is not affected by whether it is cross-domain (not only that, we also found that all tags with the "src" attribute have cross-domain capabilities, such as < script>, ,