您不需要 javascript 来执行此操作,只需使用 CSS:
<style type="text/css">
.classname {
display: none;
}
#parent:hover > div.classname {
display: block;
}
</style>
<div id="parent">
<div class="classname"></div>
</div>
但在javascript中它将是:
function OnMouseIn (elem) {
elem.getElementsByTagName("DIV")[0].style.display = "block";
}
function OnMouseOut (elem) {
elem.getElementsByTagName("DIV")[0].style.display = "none";
}
<div onmouseover="OnMouseIn (this);" onmouseout="OnMouseOut (this);">
<div class="classname" style="display:none"></div>
</div>