How to clear the default value of input_form effects

Then if I When I move the mouse away, the default value appears again. But after I input it, the default value does not appear. What should I do?

<input name="username" type="text" value="first name.last name" size="15" maxlength="60" onfocus="value=''" onblur="if(!value)value=defaultValue">
[Ctrl A Select all Note: If you need to introduce external Js, you need to refresh to execute ]

It looks like this There are still some problems. After I input, removing the mouse will not restore it to the original default value. But if I want to modify my input, it will not work. When I click the mouse, the input is cleared again

<input type="text" onblur="showSearch(this,1)" onfocus="showSearch(this)" name="KeyWord" value="输入关键字进行搜索">
[Ctrl A Select all Note: If you need to introduce external Js, you need to refresh it to execute

]

And the moderator only needs to change Cheng:

<input name="username" type="text" value="first name.last name" size="15" maxlength="60" onfocus="if (value==defaultValue)value=''" onblur="if(!value)value=defaultValue">
[Ctrl A select all Note: If you need to introduce external Js, you need to refresh to execute

]<script> function showSearch(obj,type){ if(type){ if(obj.value=="") obj.value="输入关键字进行搜索"; }else{ if(obj.value=="输入关键字进行搜索") obj.value=""; } } </script>