Let’s talk about several uses of the jQuery $ symbol

jQuery is a very popular JavaScript library that simplifies JavaScript programming and simplifies HTML document traversal and manipulation, event handling, animation, and Ajax operations.

jQuery$ symbol is one of its most commonly used functions. It has many uses, and this article will introduce some of them.

1. Selector

jQuery$ symbol can be used as a selector to select elements. You can pass the $ symbol a CSS selector and it will return jQuery objects for all elements that match that selector. For example, $("div") will return jQuery objects for all divs in the page. If you want to select a specific element, you can use CSS selectors in combination with other selectors, such as id or class name.

Example:

//选择class为example的元素
$(".example")

//选择id为foo的元素
$("#foo")

//选择带有名为"data_role"属性的所有元素
$("[data-role]")

//选择第一个p元素
$("p:first")

2. Event handling

Handling events through the jQuery$ function is very simple. Event handlers can be registered using the on() function. For example, the following code will make a button click event change the text of the button: Very convenient. For example, you can use the text() function to get or set the text content of an element:

//选中按钮元素
var button = $("button");

//注册点击事件处理函数
button.on("click", function() {
  button.text("Clicked!");
});

You can also use the append() function to add elements to the document.

3. //获取id为foo的元素文本内容
   console.log($("#foo").text());
   
   //将id为foo的元素文本内容设置为“Hello World！”
   $("#foo").text("Hello World!");

Animation effects

jQuery can also use animation effects to change the properties of elements. For example, you can use the animate() function to change the position, size, color and other attributes of an element.

//创建一个新的div元素
var newDiv = $("<div></div>");

//将新元素添加到body中
$("body").append(newDiv);

This code will move the element 10 pixels to the right, using the "slow" speed.
4. Summary

The above are several uses of the jQuery$ function. jQuery makes JavaScript programming very easy through selectors, event handling, element manipulation, and animation effects. If you haven't used jQuery before, I highly recommend giving it a try.

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