This time I will show you how to use js to bind DOM events in the project. What are the precautions for using js to bind DOM events in the project? The following is a practical case, let's take a look.
js event binding
JavaScript has three event models:
Inline model
Script model
DOM2 model
##1. Inline model
//基本废除不用 <input> <input>
2. Script model
//基本不用 var input = document.getElementsByTagName('input')[0]; //得到 input 对象 input.onclick = function () { //匿名函数执行 alert('Lee'); }; 事件处理函数 影响的元素 何时发生 onabort 图像 当图像加载被中断时 onblur 窗口、框架、所有表单对象 当焦点从对象上移开时 onchange 输入框,选择框和文本区域 当改变一个元素的值且失去焦点时 onclick 链接、按钮、表单对象、图像映射区域 当用户单击对象时 ondblclick 链接、按钮、表单对象 当用户双击对象时 ondragdrop 窗口 当用户将一个对象拖放到浏览器窗口时 onError 脚本 当脚本中发生语法错误时 onfocus 窗口、框架、所有表单对象 当单击鼠标或者将鼠标移动聚焦到窗口或框架时 onkeydown 文档、图像、链接、表单 当按键被按下时 onkeypress 文档、图像、链接、表单 当按键被按下然后松开时 onkeyup 文档、图像、链接、表单 当按键被松开时 onload 主题、框架集、图像 文档或图像加载后 onunload 主体、框架集 文档或框架集卸载后 onmouseout 链接 当图标移除链接时 onmouseover 链接 当鼠标移到链接时 onmove 窗口 当浏览器窗口移动时 onreset 表单复位按钮 单击表单的 reset 按钮 onresize 窗口 当选择一个表单对象时 onselect 表单元素 当选择一个表单对象时 onsubmit 表单 当发送表格到服务器时
3. Inline model
"DOM2-level events" defines two methods for adding events And operations to remove event handlers:addEventListener() and removeEventListener(). These two methods are included in all DOM nodes, and they both accept 3 parameters; event name, function, bubbling or captured Boolean value (true means capturing, false means bubbling)
window.addEventListener('load', function () { alert('Lee'); }, false); window.removeEventListener('load', function () { alert('Mr.Lee'); }, false)PS: IE implements two methods similar to those in DOM: attachEvent() and detachEvent(). Both methods accept
the same parameters: event name and function.
1. IE 不支持捕获,只支持冒泡; 2. IE 添加事件不能屏蔽重复的函数; 3. IE 中的 this 指向的是 window 而不是 DOM 对象。 4. 在传统事件上,IE 是无法接受到 event 对象的,但使用了 attchEvent()却可以,但有些区别。 "javascript window.attachEvent('load', function () { alert('Lee'); }, false); window.detachEvent('load', function () { alert('Mr.Lee'); }, false) "PS: The event binding functions attachEvent() and detachEvent() in IE may not be used in practice There are several reasons for using: 1. IE9 will fully support the event binding function in W3C; 2. IE’s event binding function cannot pass this; 3. IE's event binding function does not support capture; 4. After the same function is registered and bound, it is not blocked; 5. There is a memory leak problemI believe I read it You have mastered the method in the case of this article. For more exciting information, please pay attention to other related articles on the php Chinese website! Recommended reading:
How to operate angularjs cache
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Python is more suitable for data science and automation, while JavaScript is more suitable for front-end and full-stack development. 1. Python performs well in data science and machine learning, using libraries such as NumPy and Pandas for data processing and modeling. 2. Python is concise and efficient in automation and scripting. 3. JavaScript is indispensable in front-end development and is used to build dynamic web pages and single-page applications. 4. JavaScript plays a role in back-end development through Node.js and supports full-stack development.

C and C play a vital role in the JavaScript engine, mainly used to implement interpreters and JIT compilers. 1) C is used to parse JavaScript source code and generate an abstract syntax tree. 2) C is responsible for generating and executing bytecode. 3) C implements the JIT compiler, optimizes and compiles hot-spot code at runtime, and significantly improves the execution efficiency of JavaScript.

JavaScript's application in the real world includes front-end and back-end development. 1) Display front-end applications by building a TODO list application, involving DOM operations and event processing. 2) Build RESTfulAPI through Node.js and Express to demonstrate back-end applications.

The main uses of JavaScript in web development include client interaction, form verification and asynchronous communication. 1) Dynamic content update and user interaction through DOM operations; 2) Client verification is carried out before the user submits data to improve the user experience; 3) Refreshless communication with the server is achieved through AJAX technology.

Understanding how JavaScript engine works internally is important to developers because it helps write more efficient code and understand performance bottlenecks and optimization strategies. 1) The engine's workflow includes three stages: parsing, compiling and execution; 2) During the execution process, the engine will perform dynamic optimization, such as inline cache and hidden classes; 3) Best practices include avoiding global variables, optimizing loops, using const and lets, and avoiding excessive use of closures.

Python is more suitable for beginners, with a smooth learning curve and concise syntax; JavaScript is suitable for front-end development, with a steep learning curve and flexible syntax. 1. Python syntax is intuitive and suitable for data science and back-end development. 2. JavaScript is flexible and widely used in front-end and server-side programming.

Python and JavaScript have their own advantages and disadvantages in terms of community, libraries and resources. 1) The Python community is friendly and suitable for beginners, but the front-end development resources are not as rich as JavaScript. 2) Python is powerful in data science and machine learning libraries, while JavaScript is better in front-end development libraries and frameworks. 3) Both have rich learning resources, but Python is suitable for starting with official documents, while JavaScript is better with MDNWebDocs. The choice should be based on project needs and personal interests.


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