Question

我想添加一个事件管理器但是，它不起作用？

控制台显示我

"ReferenceError: event is not defined"

document.getElementsByTagName('div')[0].addEventListener("mousemove", myFunction(event));

function myFunction(event) {
    var x = event.pageX;
    var y = event.pageY;
    var coor = "Coordinates: (" + x + "," + y + ")";
    document.getElementByTagName('p')[0].textContent = coor;
}

<div> 
<p></p>
</div>

Answer 1

创建事件侦听器时，请编写该函数的唯一名称：

element.addEventListener("mousemove", myFunction);

document.getElementsByTagName('div')[0].addEventListener("mousemove", myFunction);

function myFunction(event) {
    var x = event.pageX;
    var y = event.pageY;
    var coor = "Coordinates: (" + x + "," + y + ")";
    document.getElementsByTagName('p')[0].textContent = coor;
}

div {
  background-color: red;
  width: 200px;
  height: 200px;
}

<div>
  <p></p>
</div>

Answer 2

虽然Vadim Shashkov是正确的，但背后有更多的理由。根据Mozilla（https://developer.mozilla.org/en-US/docs/Web/API/EventTarget/addEventListener）提供的文档，您为addEventListener函数赋予了值而不是函数。你需要赋予它功能，这就是为什么

document.getElementById('myDiv').addEventListener("mousemove", myFunction);

作品。

事件未定义（javascript

2 个答案: