onClick input text readonly form use inline

onClick input text readonly form use inline

I have problem with onclick input form is readonly but use it inline. I
can do only onclick is disable Example:
<input type="text" onClick=this.disabled=true />
this one is work but what I need is when onClick event is readonly I try
this :
<input type="text" onClick=this.readonly=true />
but it still not work.
if it possible please help me
I am waiting for everyone.
Thank