Analysis of DOM event bubbling examples in JQuery_jquery
This article analyzes DOM event bubbling in JQuery through examples. Share it with everyone for your reference. The specific analysis is as follows:
What is bubbling
There can be multiple events on the page, and multiple elements can respond to the same event. Suppose there are two elements on the web page, one element is nested in the other element, and both are bound to click events. At the same time, the click event is also bound to the body element.
<div id="content"> 外层div元素 <span>内层span元素</span> 外层div元素 </div>
<script type="text/javascript">
$(function(){
// 为span元素绑定click事件
$('span').bind("click",function(){
var txt = $('#msg').html() + "<p>内层span元素被点击.<p/>";
$('#msg').html(txt);
});
// 为div元素绑定click事件
$('#content').bind("click",function(){
var txt = $('#msg').html() + "<p>外层div元素被点击.<p/>";
$('#msg').html(txt);
});
// 为body元素绑定click事件
$("body").bind("click",function(){
var txt = $('#msg').html() + "<p>body元素被点击.<p/>";
$('#msg').html(txt);
});
})
</script>
When the internal span element is clicked, that is, the click event of the span element is triggered, 3 records will be output. Just clicking on the inner span element will trigger the click event bound on the outer div element and body element. This is caused by event bubbling. While clicking the span element, you also click the element div containing the span element and the element body containing the div element, and each element will respond to the click event in a specific order.
The click event of theelement will "bubble" in the following order.
1. The reason why it is called bubbling is because the event will continue to rise to the top like a bubble according to the DOM hierarchy. Problems caused by event bubbling Event bubbling may cause unexpected effects. In the above example, we originally only wanted to trigger the click event of the element, but the click events of the Event Object Since IE-DOM and standard DOM implement event objects in different ways, it becomes more difficult to obtain event objects in different browsers. To address this problem, JQuery has made the necessary extensions and encapsulations, making it easy to obtain the event object and some properties of the event object in any browser. Using event objects in programs is very simple. You only need to add a parameter to the function. The jQuery code is as follows: In this way, when the "element" element is clicked, the event object is created. This event object can only be accessed by event handling functions. After the event handling function is executed, the event object is destroyed. Stop event bubbling Stop event bubbling can prevent event handlers of other objects in the event from being executed. The stopPropagation() method is provided in JQuery to stop event bubbling. When the element is clicked, only the click event on the element will be triggered, but not the click events of the In this way, when the element or Block default behavior Elements in web pages have their own default behaviors. For example, clicking a hyperlink will jump, and clicking the "Submit" button will submit the form. Sometimes it is necessary to prevent the default behavior of elements. In JQuery, the preventDefault() method is provided to prevent the default behavior of elements. For example, in projects, it is often necessary to verify the form. When the "Submit" button is clicked, the form content is verified, such as whether an element is a required field, whether an element is 6 characters long, etc. When the form does not Prevent form submission when submission conditions are met (default behavior). When the user name is empty and you click the "Submit" button, a prompt will appear and the form cannot be submitted. The form can only be submitted after entering the user name. It can be seen that the preventDefault() method can prevent the submission of the form. If you want to stop bubbling and default behavior for the event object at the same time, you can return false in the event handling function. This is a shorthand way of calling both the stopPapagation() method and the preventDefault() method on the event object. In the form example, event.preventDefault(); can be rewritten as: return false; You can also rewrite event.stopPropaqation(); in the event bubbling example as: return false; Event capture Event capture and event bubbling are two opposite processes. Event capture is triggered from the top down. Still an example of a bubbling event, the click event of an element will be captured in the following order. 1. Obviously, event capture starts from the outermost element and then to the innermost element. Therefore, the bound click event will first be passed to the Unfortunately, not all major browsers support event capturing, and this flaw cannot be fixed with JavaScript. JQuery does not support event capture. If readers need to use event capture, please use native JavaScript directly. I hope this article will be helpful to everyone’s jQuery programming. AI-powered app for creating realistic nude photos Online AI tool for removing clothes from photos. Undress images for free AI clothes remover Swap faces in any video effortlessly with our completely free AI face swap tool! Easy-to-use and free code editor Chinese version, very easy to use Powerful PHP integrated development environment Visual web development tools God-level code editing software (SublimeText3) How to use PUT request method in jQuery? In jQuery, the method of sending a PUT request is similar to sending other types of requests, but you need to pay attention to some details and parameter settings. PUT requests are typically used to update resources, such as updating data in a database or updating files on the server. The following is a specific code example using the PUT request method in jQuery. First, make sure you include the jQuery library file, then you can send a PUT request via: $.ajax({u How to remove the height attribute of an element with jQuery? In front-end development, we often encounter the need to manipulate the height attributes of elements. Sometimes, we may need to dynamically change the height of an element, and sometimes we need to remove the height attribute of an element. This article will introduce how to use jQuery to remove the height attribute of an element and provide specific code examples. Before using jQuery to operate the height attribute, we first need to understand the height attribute in CSS. The height attribute is used to set the height of an element Click events in JavaScript cannot be executed repeatedly because of the event bubbling mechanism. To solve this problem, you can take the following measures: Use event capture: Specify an event listener to fire before the event bubbles up. Handing over events: Use event.stopPropagation() to stop event bubbling. Use a timer: trigger the event listener again after some time. Title: jQuery Tips: Quickly modify the text of all a tags on the page In web development, we often need to modify and operate elements on the page. When using jQuery, sometimes you need to modify the text content of all a tags in the page at once, which can save time and energy. The following will introduce how to use jQuery to quickly modify the text of all a tags on the page, and give specific code examples. First, we need to introduce the jQuery library file and ensure that the following code is introduced into the page: < Title: Use jQuery to modify the text content of all a tags. jQuery is a popular JavaScript library that is widely used to handle DOM operations. In web development, we often encounter the need to modify the text content of the link tag (a tag) on the page. This article will explain how to use jQuery to achieve this goal, and provide specific code examples. First, we need to introduce the jQuery library into the page. Add the following code in the HTML file: Vue.js event modifiers are used to add specific behaviors, including: preventing default behavior (.prevent) stopping event bubbling (.stop) one-time event (.once) capturing event (.capture) passive event listening (.passive) Adaptive modifier (.self)Key modifier (.key) How to tell if a jQuery element has a specific attribute? When using jQuery to operate DOM elements, you often encounter situations where you need to determine whether an element has a specific attribute. In this case, we can easily implement this function with the help of the methods provided by jQuery. The following will introduce two commonly used methods to determine whether a jQuery element has specific attributes, and attach specific code examples. Method 1: Use the attr() method and typeof operator // to determine whether the element has a specific attribute jQuery is a popular JavaScript library that is widely used to handle DOM manipulation and event handling in web pages. In jQuery, the eq() method is used to select elements at a specified index position. The specific usage and application scenarios are as follows. In jQuery, the eq() method selects the element at a specified index position. Index positions start counting from 0, i.e. the index of the first element is 0, the index of the second element is 1, and so on. The syntax of the eq() method is as follows: $("s
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$("element").bind("click",function(event){
//event : 事件对象
//...
});
$(function(){
// 为span元素绑定click事件
$('span').bind("click",function(event){
var txt = $('#msg').html() + "内层span元素被点击";
$('#msg').html(txt);
event.stopPropagation(); // 阻止事件冒泡
});
})
$('#content').bind("click",function(event){
var txt = $('#msg').html() + "<p>外层div元素被点击.<p/>";
$('#msg').html(txt);
event.stopPropagation(); // 阻止事件冒泡
});
<form action="test.html">
用户名：<input type="text" id="username" />
<br/>
<input type="submit" value="提交" id="sub"/>
</form>
$(function(){
$("#sub").bind("click",function(event){
var username = $("#username").val(); //获取元素的值
if(username==""){ //判断值是否为空
$("#msg").html("<p>文本框的值不能为空.</p>"); //提示信息
event.preventDefault(); //阻止默认行为 ( 表单提交 )
}
})
})
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