Demystifying the $ symbol in jQuery
The secret of the
$ symbol in jQuery is revealed. The
$ symbol is very important in jQuery. It is one of the core features of jQuery. This article will delve into the role and use of the $ symbol in jQuery, while providing specific code examples to help readers better understand.
1. The origin of the $ symbol
The $ symbol is a global variable defined in the jQuery library. It is actually an alias of a function. In jQuery, the $ function is mainly used to select and operate DOM elements, simplifying the operation and traversal of DOM. The $ symbol is widely used in jQuery, and almost all jQuery operations begin with the $ symbol.
2. Basic usage of $ symbol
In jQuery, you can use the $ symbol to select DOM elements, as shown below:
$(document).ready(function() {
// 执行初始化操作
$('button').click(function() {
alert("按钮被点击了！");
});
});In the above code, $(document ) selects the entire document object, and the ready() function is used to perform operations after the document is loaded. $('button') selects all button elements and adds click events to them.
3. Usage scenarios of the $ symbol
In addition to selecting DOM elements, the $ symbol can also be used to perform various operations, such as adding, deleting, and modifying the attributes and styles of elements. The following is a specific example:
// 修改元素的样式
$('p').css('color', 'red');
// 隐藏元素
$('p').hide();
// 添加新元素
$('ul').append('<li>New item</li>');4. Advanced usage of $ symbol
$ symbol also has many advanced uses in jQuery, such as chain operations, event binding, animation effects, etc. . The following is a chain operation as an example:
$('p').css('color', 'blue').slideUp(2000).slideDown(2000);In the above code, all p elements are first selected, and then the operations of modifying the color, sliding up, and sliding down are performed in sequence, realizing the continuous execution of a series of operations. .
5. Alternatives to the $ symbol
Although the $ symbol is very commonly used in jQuery, sometimes the jQuery() function can be used instead of the $ symbol, for example:
jQuery(document).ready(function() {
// 执行初始化操作
});Conclusion
$ symbol plays a vital role in jQuery, which simplifies the complexity of DOM operations and improves development efficiency. Through the introduction and examples of this article, I believe readers will have a deeper understanding of the mystery of the $ symbol in jQuery. Hope this article helps you!
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