JS实现文本框有“请输入关键字”功能

<input id="entireKeyword" type="text" style="height:21px;width:106px;color: #666666;" onblur="blurinput(this)" onfocus="changeinput(this)" size="15" title="全网检索输入框" value="请输入关键词" >

<script type="text/javascript">

        function changeinput(newid) {
            if (newid.value != "") {
                newid.value = "";
            }
        }
        function blurinput(newid) {
            if (newid.value == "") {
                newid.value = "请输入关键词"
            }
        }
</script>