Conversion between jQuery objects and DOM objects

DOM objects are some object operations inherent in Javascript. DOM objects can use Javascript's inherent methods, but they cannot use the methods in jQuery. For example, document. getElementById ("img"). src = "test.jpg"; here document. getElementById ("img") is the DOM object;
$ ("# Img"). attr ("src", "test.jpg"); and document. getElementById ("img"). src = "test.jpg ";Is equivalent, is correct,However, $ ("# img"). src = "test.jpg"; or document. getElementById ("img"). attr ("src", "test.jpg ");All are errors.

Here is an example: this is what I often write when writing jQuery: this. attr ("src", "test.jpg"); but it is an error. In fact, this is a DOM object, and. attr ("src", "test.jpg") is a jQuery method, so an error occurs. To solve this problem, we need to convert the DOM object to a jQuery object, such as $ (this). attr ("src", "test.jpg ");

 

1. convert a DOM object to a jQuery object:

For a DOM object, you only need to wrap the DOM object with $ () to obtain a jQuery object. $ (DOM object)

For example, var v = document. getElementById ("v"); // DOM object

Var $ v = $ (v); // jQuery object

After conversion, you can use the jQuery method at will.
 

2. convert a jQuery object to a DOM object:

Two conversion methods are used to convert a jQuery object to a DOM object: [index] And. get (index );

(1) The jQuery object is a data object. You can use the [index] method to obtain the corresponding DOM object.

For example, var $ v = $ ("# v"); // jQuery object

Var v = $ v [0]; // DOM object

Alert (v. checked) // checks whether the checkbox is selected

(2) jQuery provides the. get (index) method to obtain the corresponding DOM object.

For example, var $ v = $ ("# v"); // jQuery object

Var v = $ v. get (0); // DOM object

Alert (v. checked) // checks whether the checkbox is selected