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. springboot无法找到mapper😵

    今天在学习springboot的过程中遇到mapper无法找到的问题,困扰了很久

  2. Springcloud 2.x 版本 分布式配置中心

    一.什么是分布式配置中心? 就是为微服务架构中的微服务提供集中化的外部配置支持,配置中心为各个微服务应用的所有环境提供了中心化的外部配置(可能比较难理解,想知道是什么意思就要知道为什么这么配置:这么配 ...

  3. Linux 创建与删除（5）

    相对于Windows下的右键新建文件与删除,我更喜爱Linux下的命令式创建与删除,真的方便.不过Windows下也可以借助工具来实现,比如git bash.cmder等等终端工具. 创建文件 新建文 ...

  4. P2010回文日期

    这道题是2016年普及组的题,难度等级为普及-. 这道题仍然是个模拟题.有两种策略:1.枚举回文,看日期是否存在2.枚举日期,看是否是回文.显然,前者要快很多,并且准确.本蒟蒻第一次便使用了后者,bu ...

  5. [LeetCode] 95. 不同的二叉搜索树 II

    题目链接 : https://leetcode-cn.com/problems/unique-binary-search-trees-ii/ 题目描述: 给定一个整数 n,生成所有由 1 ... n ...

  6. linux：服务器代理squid安装配置

    国内上往外的网站太慢,配了个香港代理服务器.如下:当前环境: centos系统.香港服务器IP(假设:59.188.71.11)检查squid是否安装:[root@localhost ~]# rpm ...

  7. Math、Date内置对象方法整理

    Math : 内置的对象(构造函数)静态属性或静态方法.                   一.                         Math.PI : 圆周率              ...

  8. winform 自定义控件（高手）

    高手推荐:https://www.cnblogs.com/bfyx/p/11364884.html   c#Winform自定义控件-目录   前提 入行已经7,8年了,一直想做一套漂亮点的自定义控件 ...

  9. webpack 中如何使用 vue

    1. 安装vue的包: cnpm i vue -S 2. 由于 在 webpack 中,推荐使用 .vue 这个组件模板文件定义组件,所以,需要安装 能解析这种文件的 loader cnpm i vu ...

  10. 026-Cinder服务-->使用NFS作为后端存储

    以下将介绍如何使用NFS共享作为Openstack后端存储,本案例在计算节点上配置nfs [root@linux-node2 ~]# yum install -y openstack-cinder p ...