The old 'blink' tag in html has now been deprecated for example, so better to use an alternative method of implementation such as JavaScript.
You dont need javascript for blinking text, css will do fine
text-decoration: blink;
the reason why the old blink tag has been deprecated is because of the introduction of html5 and css3 which had added an extra load of functions, so quite alot of the old functions (like blink) are being passed on to css