read和onload jquery.val

Posted 2020-07-02 FEI_>.<_JI

$(document).load();

当web页面以及其附带的资源文件，如CSS，Scripts，图片等，加载完毕后执行此方法。
常用于检测页面（及其附带资源）是否加载完毕。


$(document).ready();
当页面DOM对象加载完毕，web浏览器能够运行JS时，此方法即被触发。如果你想尽快执行JS，可以使用此方法。[在html的头部的script标签中的，不处于ready()中的JS代码将早于ready()执行]


$(document).unload();
此事件在停止浏览页面的时候触发，此操作可能存在于刷新操作/F5，单击上一页按钮，进入其他页面或关闭整个tab或窗口。

总而言之，他们的调用顺序是 ready() >> load() >> unload() 。

 

 

 

$(document).load();

 

Will execute after the page along with all its contents are done loading. This means that all images, CSS (and content defined by CSS like custom fonts and images), scripts, etc. are all loaded. This happens event fires when your browser‘s "Stop" -icon becomes gray, so to speak. This is very useful to detect when the document along with all its contents are loaded.

$(document).ready();

This on the other hand will fire as soon as the web browser is capable of running your javascript, which happens after the parser is done with the DOM. This is useful if you want to execute JavaScript as soon as possible.

$(document).unload();

This event will be fired when you are navigating off the page. That could be Refresh/F5, pressing the previous page button, navigating to another website or closing the entire tab/window.

To sum up, ready() will be fired before load(), and unload() will be the last to be fired.

 

http://stackoverflow.com/questions/2683072/jquery-events-load-ready-unload

 

以上转自：http://blog.csdn.net/after2010/article/details/9037069

 

刚开始接触jquery，很多东西不熟悉在用$("#id")来获得页面的input元素的时候，发现$("#id").value不能取到值

 

后来终于在伟大的百度帮助下，找到了问题的原因： 

复制代码代码如下:

$("")是一个jquery对象，而不是一个dom element 
value是dom element的属性 
jquery与之对应的是val 
val() :获得第一个匹配元素的当前值。 
val(val):设置每一个匹配元素的值。 

所以，代码应该这样写： 

复制代码代码如下:

取值：val = $("#id")[0].value; 
赋值： 
$("#id")[0].value = "new value"; 
或者$("#id").val("new value"); 

或者这样也可以：val = $("#id").attr("value");