Javascript _ javascript skills

This article mainly introduces how js reads and parses JSON data. It analyzes the functions, usage, and JS parsing skills of json format, and has some reference value, for more information about how to read and parse JSON data in Javascript, see the following example. We will share this with you for your reference. The details are as follows:

1. What is JSON?

JSON (JavaScript Object Notation) is a lightweight data exchange format. It adopts a completely language-independent text format and is an ideal data exchange format. JSON is also a JavaScript native format.
Very suitable for server-to-JavaScript Interaction

Ii. Why JSON instead of XML

They all say this: Although there are many ideas about how XML has the cross-platform and cross-language advantages, unless it is applied to Web Services, in common Web applications, developers often use their brains for XML parsing. Whether the server generates or processes XML, or the client uses JavaScript to parse XML, it often leads to complicated code and extremely low development efficiency. In fact, for most Web applications, they do not need complicated XML to transmit data at all, and XML scalability is rarely advantageous. Many AJAX applications even directly return HTML fragments to build dynamic Web pages. Compared with returning XML and parsing it, returning HTML fragments greatly reduces the complexity of the system, but at the same time lacks some flexibility.

Iii. How to Use

The following code is an html code snippet. You can click the button to parse the json format data and alert content.

The Code is as follows:

Below is the js function code:

Var json = {contry: {area: {man: "0.12 million", women: "0.1 million" }}; // Method 1: use eval to parse var obj = eval (json); alert (obj. constructor); alert (obj. contry. area. women); // Method 2: Use the Funtion function var strJSON = "{name: 'json name '}"; // JSON var obj = new Function ("return" + strJSON) (); // converted JSON object alert (obj. name); // json name alert (obj. constructor); // json array data parsing var value1 = [{"c01": "1", "c02": "2", "c03 ": "3", "c04": "4", "c05": "5", "c06": "6", "c07": "7", "c08 ": "8", "c09": "9" },{ "c01": "2", "c02": "4", "c03": "5 ", "c04": "2", "c05": "8", "c06": "11", "c07": "21", "c08": "1 ", "c09": "12" },{ "c01": "5", "c02": "1", "c03": "4", "c04 ": "11", "c05": "9", "c06": "8", "c07": "1", "c08": "8", "c09 ": "2"}]; var obj1 = eval (value1); alert (obj1 [0]. c01); // another form of complex json var value2 = {"list": [{"password": "1230", "username ": "coolcooldool" },{ "password": "thisis2", "username": "okokok"}], "array": [{"password": "1230 ", "username": "coolcooldool"}, {"password": "thisis2", "username": "okokok"}]}; var obj2 = eval (value2 ); alert (obj2.list [0]. password );}

Iv. eval

① This form will significantly reduce the performance because it must run the Compiler

② The eval function also compromises the security of your application because it gives too much power to the evaluated text. Just like with statement execution, it reduces the language performance.

③ Function constructor is another form of eval, so it should also be avoided.

I hope this article will help you design JavaScript programs.