https://www.w3schools.com/jquery/event_ready.asp

Example

Use ready() to make a function available after the document is loaded:

$(document).ready(function(){
  $("button").click(function(){
    $("p").slideToggle();
  });
});

Definition and Usage

The ready event occurs when the DOM (document object model) has been loaded.

Because this event occurs after the document is ready, it is a good place to have all other jQuery events and functions. Like in the example above.

The ready() method specifies what happens when a ready event occurs.

Tip: The ready() method should not be used together with <body onload="">.

只能在document上使用

 

.ready()

.ready( handler )Returns: jQuery

Description: Specify a function to execute when the DOM is fully loaded.

The .ready() method offers a way to run JavaScript code as soon as the page's Document Object Model (DOM) becomes safe to manipulate.

This will often be a good time to perform tasks that are needed before the user views or interacts with the page, for example to add event handlers and initialize plugins.

When multiple functions are added via successive calls to this method, they run when the DOM is ready in the order in which they are added.

As of jQuery 3.0, jQuery ensures that an exception occuring in one handler does not prevent subsequently added handlers from executing.

Most browsers provide similar functionality in the form of a DOMContentLoaded event.

However, jQuery's .ready() method differs in an important and useful way:

If the DOM becomes ready and the browser fires DOMContentLoaded before the code calls .ready( handler ), the function handler will still be executed.

In contrast, a DOMContentLoaded event listener added after the event fires is never executed.

Browsers also provide the load event on the window object.

When this event fires it indicates that all assets on the page have loaded, including images.

This event can be watched in jQuery using $( window ).on( "load", handler ).

In cases where code relies on loaded assets (for example, if the dimensions of an image are required), the code should be placed in a handler for the load event instead.

Note that although the DOM always becomes ready before the page is fully loaded, it is usually not safe to attach a load event listener in code executed during a .ready() handler.

For example, scripts can be loaded dynamically long after the page has loaded using methods such as $.getScript().

Although handlers added by .ready() will always be executed in a dynamically loaded script, the window's load event has already occurred and those listeners will never run.

jQuery offers several ways to attach a function that will run when the DOM is ready. All of the following syntaxes are equivalent:

  • $( handler )
  • $( document ).ready( handler )
  • $( "document" ).ready( handler )
  • $( "img" ).ready( handler )
  • $().ready( handler )

As of jQuery 3.0, only the first syntax is recommended; the other syntaxes still work but are deprecated. This is because the selection has no bearing on the behavior of the .ready() method, which is inefficient and can lead to incorrect assumptions about the method's behavior. For example, the third syntax works with "document" which selects nothing. The fourth syntax waits for the document to be ready but implies (incorrectly) that it waits for images to become ready.

There is also $(document).on( "ready", handler ), deprecated as of jQuery 1.8 and removed in jQuery 3.0. Note that if the DOM becomes ready before this event is attached, the handler will not be executed.

The .ready() method is typically used with an anonymous function:

$( document ).ready(function() {

  // Handler for .ready() called.

});

Which is equivalent to the recommended way of calling:

$(function() {

  // Handler for .ready() called.

});

jQuery .ready()的更多相关文章

  1. jQuery-1.9.1源码分析系列（六） 延时对象应用——jQuery.ready

    还记不记得jQuery初始化函数jQuery.fn.init中有这样是一个分支 //document ready简便写法$(function(){…}) } else if ( jQuery.isFu ...

  2. jQuery Ready 与 Window onload 的区别(转)

    “我们都知道,很多时候,在页面加载完后都需要做一些相应的初始化动作.例如,运行某些js特效,设置表单等等.怎么知道页面加载完了呢?一 般情况下都是设置body标签的onload监听window的loa ...

  3. jquery ready 延迟

    $.holdReady(true);//延迟 $.holdReady(false);//解延迟 用于下载文件的时候,异步操作 $.holdReady(true); $.getScript(" ...

  4. (十六)JQuery Ready和angularJS controller的运行顺序问题

    项目中使用了JQuery和AngularJS框架,近期定位一个问题,原因就是JQuery Ready写在了angularJS controller之前,导致JQuery选择器无法选中须要的元素(由于a ...

  5. jquery ready方法实现原理 内部原理

    jquery ready方法实现原理 内部原理 今天闲来无事研究研究jquery.ready()的内部实现,看JQ的源码一头雾水,由于自己很菜了,于是翻了翻牛人的播客,讲述详细,收获颇多. 先普及一下 ...

  6. jQuery.ready() 函数详解

    jQuery.ready() 函数详解 ready()函数用于在当前文档结构载入完毕后立即执行指定的函数. 该函数的作用相当于window.onload事件. 你可以多次调用该函数,从而绑定多个函数, ...

  7. jquery ready方法实现原理

    先看这两句代码: window.addEventListener('load',loaded,false); document.addEventListener('DOMContentLoaded', ...

  8. jquery ready和window onload区别

    window onload是指标签加载完成,并且标签资源加载完成: jquery ready是指标签加载完成,标签资源可能未加载完成 $(document).ready(function(){});= ...

  9. DOMContentLoaded vs jQuery.ready vs onload, How To Decide When Your Code Should Run

    At a Glance Script tags have access to any element which appears before them in the HTML. jQuery.rea ...

  10. JavaScript window.onload 事件和 jQuery ready 函数有何不同？

    JavaScript window.onload 事件和 jQuery ready 函数之间的主要区别是,前者除了要等待 DOM 被创建还要等到包括大型图片.音频.视频在内的所有外部资源都完全加载.如 ...

随机推荐

  1. SELECT 与 SET给标量赋值

    本文转自 :https://blog.csdn.net/perddy/article/details/4033406 SQL Server推荐使用 SET 而不是 SELECT 对变量进行赋值.当表达 ...

  2. Kinect V2入门之数据获取步骤

    在Kinect for windows SDK2.0中,获取并处理数据源接口步骤如下: Sensor -> Source -> Reader -> Frame -> Data ...

  3. docker下部署kafka集群(多个broker+多个zookeeper)

    网上关于kafka集群的搭建,基本是单个broker和单个zookeeper,测试研究的意义不大.于是折腾了下,终于把正宗的Kafka集群搭建出来了,在折腾中遇到了很多坑,后续有时间再专门整理份搭建问 ...

  4. E - 盒子游戏

    有两个相同的盒子,其中一个装了n个球,另一个装了一个球.Alice和Bob发明了一个游戏,规则如下:Alice和Bob轮流操作,Alice先操作每次操作时,游戏者先看看哪个盒子里的球的数目比较少,然后 ...

  5. 简洁的Asp.net菜单控件

    http://www.cnblogs.com/ruinet/archive/2009/11/10/1599984.html asp.net自带的菜单控件采用的table和javascript,导致生成 ...

  6. Tomcat编译jsp生成Servlet文件的存放位置

    转自:http://www.cnblogs.com/Leon5/archive/2010/12/07/1899300.html Tomcat将jsp编译成servlet后的文件存放在\work\Cat ...

  7. [七月挑选]使用idea创建spring boot 项目

    title: 使用idea创建spring boot 项目 参考lindaZ的IntelliJ IDEA 创建spring boot 的Hello World 项目 1.Open IDEA,choos ...

  8. AVCaptureSession拍照，摄像，载图总结

    AVCaptureSession [IOS开发]拍照,摄像,载图总结 1 建立Session  2 添加 input  3 添加output  4 开始捕捉 5 为用户显示当前录制状态 6 捕捉 7 ...

  9. JavaEE高级-Struts2学习笔记

    Struts2是一个用来来发MVC应用的框架,它提供了Web应用程序开发过程中一些常见问题的解决方案: - 对来自用户的输入数据进行合法的验证 - 统一的布局 - 可扩展性. - 国际化和本地化 - ...

  10. python socket--TCP解决粘包的方法

    1.为什么会出现粘包?? 让我们基于tcp先制作一个远程执行命令的程序(1:执行错误命令 2:执行ls 3:执行ifconfig) 注意注意注意: res=subprocess.Popen(cmd.d ...