鼠标点击输入框时value消失，输入框空白时移走鼠标value重现

<input type="text" value="denis@getcraftwork.com" class="ID" onfocus="javascript:if(this.value='denis@getcraftwork.com')this.value=''" onblur="if(this.value=='')this.value='denis@getcraftwork.com'">