


What are json and jsonp, jQuery json examples are explained in detail_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:
// 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 ,


JavaScript is widely used in websites, mobile applications, desktop applications and server-side programming. 1) In website development, JavaScript operates DOM together with HTML and CSS to achieve dynamic effects and supports frameworks such as jQuery and React. 2) Through ReactNative and Ionic, JavaScript is used to develop cross-platform mobile applications. 3) The Electron framework enables JavaScript to build desktop applications. 4) Node.js allows JavaScript to run on the server side and supports high concurrent requests.

Python is more suitable for data science and automation, while JavaScript is more suitable for front-end and full-stack development. 1. Python performs well in data science and machine learning, using libraries such as NumPy and Pandas for data processing and modeling. 2. Python is concise and efficient in automation and scripting. 3. JavaScript is indispensable in front-end development and is used to build dynamic web pages and single-page applications. 4. JavaScript plays a role in back-end development through Node.js and supports full-stack development.

C and C play a vital role in the JavaScript engine, mainly used to implement interpreters and JIT compilers. 1) C is used to parse JavaScript source code and generate an abstract syntax tree. 2) C is responsible for generating and executing bytecode. 3) C implements the JIT compiler, optimizes and compiles hot-spot code at runtime, and significantly improves the execution efficiency of JavaScript.

JavaScript's application in the real world includes front-end and back-end development. 1) Display front-end applications by building a TODO list application, involving DOM operations and event processing. 2) Build RESTfulAPI through Node.js and Express to demonstrate back-end applications.

The main uses of JavaScript in web development include client interaction, form verification and asynchronous communication. 1) Dynamic content update and user interaction through DOM operations; 2) Client verification is carried out before the user submits data to improve the user experience; 3) Refreshless communication with the server is achieved through AJAX technology.

Understanding how JavaScript engine works internally is important to developers because it helps write more efficient code and understand performance bottlenecks and optimization strategies. 1) The engine's workflow includes three stages: parsing, compiling and execution; 2) During the execution process, the engine will perform dynamic optimization, such as inline cache and hidden classes; 3) Best practices include avoiding global variables, optimizing loops, using const and lets, and avoiding excessive use of closures.

Python is more suitable for beginners, with a smooth learning curve and concise syntax; JavaScript is suitable for front-end development, with a steep learning curve and flexible syntax. 1. Python syntax is intuitive and suitable for data science and back-end development. 2. JavaScript is flexible and widely used in front-end and server-side programming.

Python and JavaScript have their own advantages and disadvantages in terms of community, libraries and resources. 1) The Python community is friendly and suitable for beginners, but the front-end development resources are not as rich as JavaScript. 2) Python is powerful in data science and machine learning libraries, while JavaScript is better in front-end development libraries and frameworks. 3) Both have rich learning resources, but Python is suitable for starting with official documents, while JavaScript is better with MDNWebDocs. The choice should be based on project needs and personal interests.


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