attr method in jquery

jQuery is a well-known JavaScript library that allows developers to process HTML documents, dynamic effects, Ajax interactions, etc. in a simpler way. Among them, the attr() method is an important feature in the jQuery library, used to get or set the attributes of the specified element. In this article, we will delve into the attr() method in jQuery to give readers a deeper understanding of its use.

1. Understanding the attr() method

First, let us look at how attr() is defined.

$('div').attr('name', 'value');

It can be seen that the grammatical structure of attr() is very intuitive and simple. It can find the elements that need to be processed from the DOM document through the selector method. Then, use the attr() method to get or set its attributes. Among them, the first parameter specifies the attribute name that needs to be obtained or set, and the second parameter specifies the attribute value.

Let’s take a look at the specific application of this function:

1. Get the specified element attributes:

   $('div').attr('class ') //Return the 'class' attribute

2. Set the specified element attribute:

   $('div').attr('class', 'my-class' ); //Set the 'class' attribute to 'my-class'

It should be noted that the attr() method can operate the attributes of all HTML elements, including id, class, style, href, src, etc. At the same time, you can also operate on custom attributes.

2. How to use the attr() method

Next, we will introduce some examples to help readers better understand how to use the attr() method.

1. Get or set element id:

   //Set id to 'divId'
   var div = $('div');
   div. attr('id', 'divId');

   //Get the id number
   var divId = div.attr('id');

2. Get Or set the specified element class:

   //Set class to 'my-class'
   var div = $('div');
   div.attr('class', 'my-class ');

   //Get the class name
   var divClass = div.attr('class');

3. Get or set custom attributes:

   //Set the value of data-userId attribute
   $('a').attr('data-userId', '123456');

   //Get the value of data-userId
   var userId = $('a').attr('data-userId');

These examples can help readers better understand the usage of the attr() method. In actual use, the attr() method has a very wide scope of application. It can be used to add, obtain, and modify numerous attributes in DOM elements.

3. Some practical cases

1. Set the attribute value in advance:

   $('input#text').attr({

    name:'myName',
    value:'myValue'

   });

2. Select elements through the 'checked' attribute:

   $('input[type="checkbox"]').removeAttr( 'checked');

3. Dynamic loading of an image address:

   $('img').attr('src', '/my-image.png ');

In short, the attr() method makes jQuery simpler and more powerful, and it also allows us to improve efficiency in development.

4. Summary

In short, the attr() method in jQuery allows developers to get and set the attributes of HTML elements. By using and understanding it, we can operate DOM elements more efficiently, which facilitates us to quickly implement functions and special effects during development. I hope this article can help readers better understand the use of jQuery's attr() method and speed up development.

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