Why alert box not appearing in the first code or what steps shall i take to make alert box working in the first code with the value in name textbox.

Because you're not paying attention :)

See CGI button -onClick not working

Examine the generated HTML and you'll see there is no id='name'

$ perl -MCGI -le " print CGI->textfield(q[name]) "
<input type="text" name="name"  />
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