Is it necessary to create script tag in html to show alert box?

Question

Can't we just make js file, code there and show alert box in html without using script tag ?

Answer 1

no: to execute a js script (either in external file or embeded in script tag), you must include it in an html page...

however, as html is a very permissive language, you could simply start your js file with an opening script tag and end it with a closing one (and save it with '.html' extension): browsers would make the minimal html code for empty page... this will not be a valid html file, but should work as you expect ;)