Revealing the secret of $ in jQuery

jQuery is a very popular JavaScript library. It simplifies the implementation of DOM operations, event processing, animation effects and other functions, greatly improving the work efficiency of developers. In jQuery, the $ sign is a very important concept and it appears in almost every jQuery code snippet. The $ symbol is a global function in jQuery, which is used to replace the common native JavaScript methods such as document.getElementById() or document.querySelector(), allowing developers to operate DOM elements more conveniently. The specific functions of the

$ symbol include but are not limited to the following:

1. Select elements: Use the $ symbol to quickly select one or more DOM elements, such as through the element's ID, Class name, tag name, etc. to select.

// 通过ID选择元素
var elementById = $("#myElementId");

// 通过类名选择元素
var elementsByClass = $(".myElements");

// 通过标签名选择元素
var elementsByTag = $("div");

2. Perform operations: The $ symbol can also perform various DOM operations, such as setting element attributes, styles, and registering events.

// 设置元素的文本内容
$("#myElement").text("Hello, World!");

// 改变元素的背景颜色
$("#myElement").css("background-color", "red");

// 注册点击事件
$("#myButton").click(function() {
    alert("Button clicked!");
});

3. Chain operation: The $ symbol in jQuery supports chain operation, which can operate on multiple DOM elements at one time, simplifying code writing.

$("div").addClass("highlight").css("color", "blue").fadeOut(1000);

In addition to the above basic usages, the $ symbol has many other applications in jQuery, such as animation effects, AJAX requests, etc. In jQuery plug-ins, the $ symbol is also widely used and can be used to call plug-in methods or set plug-in parameters.

In general, the secret of the $ symbol in jQuery lies in its simplicity, flexibility and powerful functions. By having an in-depth understanding of the usage and principles of the $ symbol, developers can better utilize the jQuery library for front-end development and improve work efficiency and code quality.

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