JavaScript实现文本框中默认显示背景图片在获得焦点后消失的方法

<form name="searchform" id="search-form">
<div>
<b>Search</b>
<input type="text" name="txtInput"
title="Enter the terms you wish to search for." />
<input type="submit" value="GO!" class="submit"
style="cursor: pointer;" />
</div>
</form>

<script type="text/javascript" language="javascript">
(function() {
var id = document.getElementById('search-form');
if (id && id.txtInput) {
var name = id.txtInput;
var unclicked = function() {
if (name.value == '') {
name.style.background = '#FFFFFF url(images/googbg.png) left no-repeat';
}
};
var clicked = function() {
name.style.background = '#ffffff';
};
name.onfocus = clicked;
name.onblur = unclicked;
unclicked();
}
})();
</script>