Jquery knowledge point 2 jquery operations on arrays _ jquery

As we all know, Jquery is an efficient encapsulation of JavaScript, so the array to be operated by Jquery is an array in JavaScript. in JavaScript, we use for and for-in for Array Operations, in Jquery, $. map (), $. each () is used to operate an array. First, it is an ordinary array (an array with an index of an integer ):
$. Map (arr, fn );
Call the fn function to process each element in the array one by one. The fn function returns a new array.

The Code is as follows:

Var arr = [9, 8, 7, 6, 5, 4, 3, 2, 1];
Var newarr = $. map (arr, function (item) {return item * 2 });
Alert (newarr );

$. Each (array, fn) calls the fn function to process each element of the array. No return value is returned.

The Code is as follows:

Var arr = [9, 8, 7, 6, 5, 4, 3, 2, 1];
$. Each (arr, function (key, value) {alert ("key:" + key + "value:" + value );});

You can also omit the function parameter. In this case, you can obtain the value of the current element to be traversed.

The Code is as follows:

Var arr = [9, 8, 7, 6, 5, 4, 3, 2, 1];
$. Each (arr, function () {alert (this );});

Then there is an array of key-value pairs indexed as strings. For such arrays,
$. Each (array, fn) is generally used for operations:

The Code is as follows:

Var arr = {"jim": "11", "tom": "12", "lilei": "13 "};
$. Each (arr, function (key, value) {alert ("name:" + key + "Age:" + value );});

Of course, you can also use a function without parameters to traverse;
This type of data can be obtained from the server as follows:
Server:

The Code is as follows:

<% @ WebHandler Language = "C #" Class = "Handler" %>
Using System;
Using System. Web;
Using System. Web. Script. Serialization;
Using System. Collections. Generic;
Public class Handler: IHttpHandler {
Public void ProcessRequest (HttpContext context ){
Context. Response. ContentType = "text/plain ";
Person p1 = new Person {Age = "22", Name = "tom "};
Person p2 = new Person {Age = "23", Name = "jim "};
Person p3 = new Person {Age = "24", Name = "lilei "};
IList Persons = new List {P1, p2, p3 };
JavaScriptSerializer js = new JavaScriptSerializer ();
String s = js. Serialize (persons );
Context. Response. Write (s );
}
Public class Person
{
Public string Name {get; set ;}
Public string Age {get; set ;}
}
Public bool IsReusable {
Get {
Return false;
}
}
}

Three person objects are instantiated first, then put into a collection, and finally serialized into a string to flow to the client;

Client:

The Code is as follows: