在 Javascript/jQuery 中 (e) 是什么意思? [英] In Javascript/jQuery what does (e) mean?

问题描述

我是 JavaScript/jQuery 的新手，我一直在学习如何创建函数.许多函数都出现在括号中的 (e) 中.让我告诉你我的意思:

I am new to JavaScript/jQuery and I've been learning how to make functions. A lot of functions have cropped up with (e) in brackets. Let me show you what I mean:

$(this).click(function(e) {
    // does something
});

函数似乎总是不使用 (e) 的值，那为什么它经常出现呢?

It always appears that the function doesn't even use the value of (e), so why is it there so often?

推荐答案

e 是 event 对象的简短 var 引用，该对象将传递给事件处理程序.

e is the short var reference for event object which will be passed to event handlers.

事件对象本质上有很多有趣的方法和属性，可以在事件处理程序中使用.

The event object essentially has lot of interesting methods and properties that can be used in the event handlers.

在您发布的示例中，点击处理程序是一个 MouseEvent

In the example you have posted is a click handler which is a MouseEvent

$(<element selector>).click(function(e) {
    // does something
    alert(e.type); //will return you click
}

DEMO - 鼠标事件 DEMO 使用 e.which 和 e.type

一些有用的参考:

http://api.jquery.com/category/events/

http://www.quirksmode.org/js/events_properties.html

http://www.javascriptkit.com/jsref/event.shtml

http://www.quirksmode.org/dom/events/index.html

http://www.w3.org/TR/DOM-Level-3-Events/#event-types-list

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