Input how to clear the default value _ form effects

<input name= "username" type= "text" value= "name Name.last" "Size=" "maxlength=" "onfocus=" "this.value=" " >
Then if I move the mouse again, the default value, and when I entered, then do not appear the default value, how to deal with it?

<input name= "username" type= "text" value= "name Name.last" "Size=" "maxlength=" onfocus= "value=" "onblur=" if (!value) Value=defaultvalue ">
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This seems to be still some problems, when I entered the mouse will not revert to the original default value, but if I want to modify my input, it will not. The mouse point up, input was emptied

<input type= "text" onblur= "Showsearch (this,1)" onfocus= "Showsearch (This)" Name= "KeyWord" value= "Enter keyword for search"/> <script> function Showsearch (obj,type) {if (type) {if (obj.value== ") obj.value=" Enter keywords for search "; }else{if (obj.value== "Enter keyword for search") obj.value= ""; }} </script>
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And the moderator's only change:

<input name= "username" type= "text" value= "A/name.last name "Size=" maxlength= "onfocus=" if (value==defaultvalue) value= ' "onblur=" if (!value) value=defaultvalue "> </ textarea>
[ CTRL + A All SELECT Note: If you need to introduce external JS need to refresh to perform]