Javascript：当鼠标悬停时，在dom树中获取元素

问题描述：

使用时：

document.onmouseover = function(e) {}

有没有一个属性给我在dom树中的元素？

Is there a property which gives me the element in the dom tree ?

例如我可以设置一个样式为 e.srcElement
但是，如何以后再访问这个元素（例如）重设其样式？
我怎么知道dom树中的哪个地方？
我想要把它放在整个页面转储中。

For example, I can set a style to e.srcElement But, how can I later access this element to (for example) reset its style ? And how can I know at which place in the dom tree it is ? I want to be able to situate it in the whole page dump.

非常感谢。

为了解决稍后重新访问元素的问题，我尝试了这个但是不起作用：

To solve the problem about reaccessing the element later, I tried this but it doesn't work :

var lastelem;

document.onmouseover = function(e) {

  if (lastelem != null){
    lastelem.style.border = "0px";
  }

  if (e===undefined) e= window.event;
  var target= 'target' in event? event.target : event.srcElement;
  document.getElementById('display').value = target.tagName;
  target.style.border = "1px";
  lastelem = target;
};

谢谢

答

哪个HTML元素是事件的目标？（在Quirksmode上.org，Peter-Paul Koch）。另请参阅 target 属性。

Which HTML element is the target of the event? (on Quirksmode.org, by Peter-Paul Koch). Also have a look at the target attribute of the Event object in W3C DOM Level 2 Event Model.

<!DOCTYPE html>
<html>
  <head>
    <title>target test</title>
    <style>
      *        { border: 1px solid #fff }
      .trigger { background: lightgreen }
    </style>
  </head>
  <body>
    <p class="trigger">Trigger testCase().</p>
    <p class="trigger">Trigger testCase().</p>
    <p class="trigger">Trigger testCase().</p>
    <p id="display"></p>
    <script>
var lastelem;

document.onmouseover = function (e) {
        var event = e || window.event;

        if (lastelem) {
                lastelem.style.border = "1px solid #fff";
        }

        var target = event.target || event.srcElement;
        document.getElementById('display').innerHTML = target.previousSibling.tagName +
            " | " + target.tagName + " | " + (target.nextSibling ? target.nextSibling.tagName : "X");
        target.style.border = "1px solid";
        lastelem = target;
};
    </script>
  </body>
</html>

Javascript：当鼠标悬停时，在dom树中获取元素

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