如下所示：
复制代码代码如下：
<！doctype html public " - // w3c // dtd xhtml 1.0 transitional // en" "http://www.w3.org/tr/xhtml1/dtd/xhtml1-transitional.dtd">
<html xmlns = "http://www.w3.org/1999/xhtml">
<head>
<Meta http-equiv = "content-type" content = "text /html; charset = utf-8" />
<title>无标题文档</title>
<style type = "text/css">
.ClearFieldBlurred {
色：#ccc;
フォントスタイル：イタリック;
font-weight：正常;
幅：150px;
}
.ClearFieldactive {
色：＃4e4e4e;
font-weight：bold;
幅：150px;
}
</style>
<script type = "text/javascript">
関数ClearFiled（）{
var bbb = document.getElementById（ "BBB"）;
if（bbb.value == "bbb"）{
bbb.value = '';
bbb.classname = 'clearfieldactive';
}
}
window.document.onmousedown = function（）{
var bbb = document.getElementById（ 'bbb'）;
if（bbb.value == ""）{
bbb.value = 'bbb';
bbb.classname = 'clearfieldblurred';
}
}
</script>
</head>
<body>
<入力型= "text" id = "aaa" value = "aaa" onfocus = "if（this.value == 'aaa'）{this.value = ''; this.classname = 'clearfieldactive';}" onblur = "if（this.value == ''）{this.value = 'aaa'; this.classname = 'clearfieldblurred';}"/>
<br />
<入力型= "text" id = "bbb" value = "bbb" onclick = "clearfiled（）" />
</body>
</html>