Before the jQuery 3.0 version, the classic usage of ready was to use an anonymous function, like this:
$(document).ready(function() { // Handler for .ready() called. });
jQuery 3.0 ready() changes
Before the release of jQuery 3.0, there were the following methods called ready method:
Operating on document elements: $(document).ready(handler);
Operating on empty elements: $().ready(handler);
Or directly (that is, not on a specific element ) Operation: $(handler);
All named variants above are functionally equivalent. No matter which element it is, its specified handler will be called after the DOM is loaded. In other words, the completion of DOM loading here does not mean that a specific element in the document, such as the img element, has been loaded. On the contrary, what it means here is that the entire DOM tree has been loaded.
In jQuery 3.0, all ready methods except $(handler) are deprecated.
Official statement:
This is because the selector is not connected to ready(), which is not only inefficient but also causes the browser engine to make incorrect assumptions about the behavior of this method.
The difference between ready event and load event
The ready event will be triggered when the DOM is loaded and the element can be safely accessed. On the other hand, the load event is triggered after the DOM and all resources are loaded.
You can use the load event as follows:
$(window).on("load", function(){ // Handler when all assets (including images) are loaded });
In this case, not only do you have to wait until the DOM structure can be fully accessed, but you also need to wait until all image resources are completely loaded (the loading time depends on the image file size) to execute the function.
You may not need the load event for normal DOM operations, but if you want to display a rotating loader style before all resources are loaded, for example, or you want to use JS to calculate the size of the image, this Might be a good choice.
You may not need jQuery.ready()
ready method ensures that code is only executed when all DOM elements can be safely manipulated. But what does this mean? This means that when the js code you want to execute is embedded in a certain fragment in HTML, the browser must also load the following elements before it can be executed.
Like the following example:
<!doctype html> <html> <head> <meta charset="utf-8"> <title>.ready() tutorial</title> <script src="https://cdn.jsdelivr.net/jquery/latest/jquery.min.js"></script> <script> $(function(){ // .ready() callback, is only executed when the DOM is fully loaded var length = $("p").length; // The following will log 1 to the console, as the paragraph exists. // This is the evidence that this method is only called when the // DOM is fully loaded console.log(length); }); </script> </head> <body> <p>I'm the content of this website</p> </body> </html>
If the javascript code you want to execute is placed at the end of the body, you may not need to use the ready() method, because you may try to manipulate it when the browser parses the javascript And the accessed DOM element has been loaded:
<!doctype html> <html> <head> <meta charset="utf-8"> <title>.ready() tutorial</title> </head> <body> <p>I'm the content of this website</p> <script src="https://cdn.jsdelivr.net/jquery/latest/jquery.min.js"></script> <script> var length = $("p").length; // The following will log 1 to the console, as the paragraph exists. console.log(length); </script> </body> </html>
Native JavaScript ready() replacement
For modern browsers and IE9+, you can achieve the same function of ready() by listening to the DOMContentLoaded event:
document.addEventListener("DOMContentLoaded", function(){ // Handler when the DOM is fully loaded });
However, please note that if the event has already been emitted, the callback will not be executed. To ensure that the callback always runs, jQuery checks the "readyState" property of the document reference) and executes the callback function immediately if the property value changes to complete:
var callback = function(){ // Handler when the DOM is fully loaded }; if ( document.readyState === "complete" || (document.readyState !== "loading" && !document.documentElement.doScroll) ) { callback(); } else { document.addEventListener("DOMContentLoaded", callback); }
includes the domReady library, which has implemented this solution.
Old version of IE browser
For IE8 and below browsers, you can use the onreadystatechange event to monitor the readyState property of the document:
document.attachEvent("onreadystatechange", function(){ // check if the DOM is fully loaded if(document.readyState === "complete"){ // remove the listener, to make sure it isn't fired in future document.detachEvent("onreadystatechange", arguments.callee); // The actual handler... } });
Or you can use the Load event, such as jQuery, so that you can Runs on any browser. This also causes a delay as it waits for all assets to be loaded.
Note that in this solution you also check readyState, as mentioned above, to ensure that the callback can always be executed.

实现方法:1、用“$("img").delay(毫秒数).fadeOut()”语句,delay()设置延迟秒数;2、用“setTimeout(function(){ $("img").hide(); },毫秒值);”语句,通过定时器来延迟。

区别:1、axios是一个异步请求框架,用于封装底层的XMLHttpRequest,而jquery是一个JavaScript库,只是顺便封装了dom操作;2、axios是基于承诺对象的,可以用承诺对象中的方法,而jquery不基于承诺对象。

修改方法:1、用css()设置新样式,语法“$(元素).css("min-height","新值")”;2、用attr(),通过设置style属性来添加新样式,语法“$(元素).attr("style","min-height:新值")”。

增加元素的方法:1、用append(),语法“$("body").append(新元素)”,可向body内部的末尾处增加元素;2、用prepend(),语法“$("body").prepend(新元素)”,可向body内部的开始处增加元素。

删除方法:1、用empty(),语法“$("div").empty();”,可删除所有子节点和内容;2、用children()和remove(),语法“$("div").children().remove();”,只删除子元素,不删除内容。

在jquery中,apply()方法用于改变this指向,使用另一个对象替换当前对象,是应用某一对象的一个方法,语法为“apply(thisobj,[argarray])”;参数argarray表示的是以数组的形式进行传递。

on()方法有4个参数:1、第一个参数不可省略,规定要从被选元素添加的一个或多个事件或命名空间;2、第二个参数可省略,规定元素的事件处理程序;3、第三个参数可省略,规定传递到函数的额外数据;4、第四个参数可省略,规定当事件发生时运行的函数。

去掉方法:1、用“$(selector).removeAttr("readonly")”语句删除readonly属性;2、用“$(selector).attr("readonly",false)”将readonly属性的值设置为false。


Hot AI Tools

Undresser.AI Undress
AI-powered app for creating realistic nude photos

AI Clothes Remover
Online AI tool for removing clothes from photos.

Undress AI Tool
Undress images for free

Clothoff.io
AI clothes remover

AI Hentai Generator
Generate AI Hentai for free.

Hot Article

Hot Tools

SAP NetWeaver Server Adapter for Eclipse
Integrate Eclipse with SAP NetWeaver application server.

MinGW - Minimalist GNU for Windows
This project is in the process of being migrated to osdn.net/projects/mingw, you can continue to follow us there. MinGW: A native Windows port of the GNU Compiler Collection (GCC), freely distributable import libraries and header files for building native Windows applications; includes extensions to the MSVC runtime to support C99 functionality. All MinGW software can run on 64-bit Windows platforms.

VSCode Windows 64-bit Download
A free and powerful IDE editor launched by Microsoft

MantisBT
Mantis is an easy-to-deploy web-based defect tracking tool designed to aid in product defect tracking. It requires PHP, MySQL and a web server. Check out our demo and hosting services.

mPDF
mPDF is a PHP library that can generate PDF files from UTF-8 encoded HTML. The original author, Ian Back, wrote mPDF to output PDF files "on the fly" from his website and handle different languages. It is slower than original scripts like HTML2FPDF and produces larger files when using Unicode fonts, but supports CSS styles etc. and has a lot of enhancements. Supports almost all languages, including RTL (Arabic and Hebrew) and CJK (Chinese, Japanese and Korean). Supports nested block-level elements (such as P, DIV),
