title 属性设置或返回元素的参考性的标题。
areaObject.title=title
本例返回 "Venus" 的 title:
<html>
<body>
<img src ="planets.gif"
width="145" height="126"
alt="Planets"
usemap ="#planetmap" />
<map name ="planetmap">
<area id="venus" shape="circle"
coords ="124,58,8"
title="Venus"
href ="venus.htm" />
</map>
<p>Venus' advisory title (mouse over the Venus planet):
<script type="text/javascript">
x=document.getElementById('venus')
document.write(x.title
)
</script>
</p>
</body>
</html>