Analysis of the relationship between jQuery objects and DOM elements

jQuery is a very popular JavaScript library that provides developers with many convenient methods to manipulate DOM elements. During the development process, we often encounter situations where jQuery objects and DOM elements are used, and the relationship between them is very important. This article will deeply explore the relationship between jQuery objects and DOM elements, and analyze it with specific code examples.

First, let’s start with what jQuery objects and DOM elements are. DOM elements are real elements in web pages, such as div, p, span and other tag elements. They can be operated through native JavaScript methods or attributes, such as document.getElementById(), element.innerHTML, etc. The jQuery object is an object that manipulates DOM elements through methods encapsulated by the jQuery library. It is a collection that contains a series of DOM elements.

In jQuery, we usually obtain DOM elements through selectors, and then convert these DOM elements into jQuery objects so that they can be manipulated through the methods provided by jQuery. Here is a simple code example:

// 获取id为myDiv的元素，并转换为jQuery对象
var $myDiv = $('#myDiv');

// 修改元素的文本内容
$myDiv.text('这是一个jQuery对象操作的DOM元素');

In this example, we select the element with the id myDiv through jQuery's selector method $(), and then convert it to jQuery Object $myDiv. Next, we used the .text() method to modify the text content of the element.

In addition, it should be noted that jQuery objects and DOM elements are not exactly the same, there are some differences between them. An important difference is that operating DOM elements through native JavaScript directly operates on the element itself, while operating DOM elements through jQuery objects operates on all elements in the collection. The following is a comparison example:

// 使用jQuery对象操作DOM元素
$('#myList li').addClass('highlight');

// 使用原生JavaScript操作DOM元素
var listItem = document.getElementById('myList').getElementsByTagName('li');
listItem[0].classList.add('highlight');

In the above example, we used jQuery objects and native JavaScript to add highlight styles to the li elements in the list. As you can see, when operating through the jQuery object, the style will be applied to all elements that meet the selector conditions, while operating through native JavaScript can only be applied to a specific element.

In general, the jQuery object is a collection that encapsulates a series of DOM elements. It operates these elements through the methods provided by jQuery, making development more convenient and efficient. When using jQuery, developers need to pay attention to converting DOM elements into jQuery objects for operation, so that multiple DOM elements can be managed and operated uniformly. I hope this article will be helpful in understanding the relationship between jQuery objects and DOM elements.

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