为什么“事件"在 Chrome 中全局可用，但在 FF 中不可用? [英] Why is 'event' available globally in Chrome but not FF?

问题描述

在解决另一个问题的答案时，出现了一个与 event 对象相关的奇怪错误，该对象可在匿名函数中使用而无需传入.在 Chrome 中，以下工作正常，但 FF 抛出一个错误.

While working on an answer for another question, a strange bug came up related to the event object being available in an anonymous function without being passed in. In Chrome the below works fine, but FF throws an error.

$(document).ready(function() {
  $("#uspsSideboxTrackingClose").click(function() {
    event.preventDefault();
    console.log(event);
  });
});

铬:

火狐:

ReferenceError: 事件未定义

ReferenceError: event is not defined

<小时>

众所周知

---

It is already known that

$("#uspsSideboxTrackingClose").click(function(event) { .. }

适用于两种浏览器.这里 是有问题的代码.这是 Chrome 或 FF 的错误，还是两种浏览器的预期行为?哪个浏览器合适?

works in both browsers. Here is the offending code. Is this a bug with Chrome or FF, or intended behavior by both browsers? Which browser is right?

推荐答案

在IE中，事件对象是一个全局对象，(它不传递给处理函数)但作为一个全局对象访问.您还可以将其作为窗口对象的属性来访问，例如 window.event

In IE, the event object was a global object, (which is not passed to the handler function) but accessed as a global object. You can also access it as a property of the window object like window.event

在 FF 和其他浏览器中，事件对象作为参数传递，因为在 FF 中没有名为 event 的全局属性，因此您会收到错误消息.

In in FF and other browsers the event object was passed as an argument, since in FF there is no global property called event, you are getting the error message.

在 chrome 中，他们添加了对这两个功能的支持，因此您将获取事件对象作为全局引用和参数.

In chrome they have added support for both these features, so you will get the event object as a global reference and as an argument.

但是由于您使用的是 jQuery，因此 jQuery 会规范化这两种行为，并将始终将事件对象作为参数传递给事件处理程序.

But since you are using jQuery, jQuery normalizes these 2 behaviors and will always pass the event object as an argument to the event handler.

$(document).ready(function () {
    $("#uspsSideboxTrackingClose").click(function (event) {
        event.preventDefault();
        console.log(event);
    });
});

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