使用onblur和onfocus属性:
<input type="text" value="默认值" onblur="if(this.value==''){this.value='默认值'}" onfocus="if(this.value=='默认值'){this.value=''}" />
使用onblur和onfocus属性:
<input type="text" value="默认值" onblur="if(this.value==''){this.value='默认值'}" onfocus="if(this.value=='默认值'){this.value=''}" />