Why do you see colons while calling a javascript function in html sometimes?

Question

A lot of the time I see people calling javascript functions using colon (:).

Like onclick=\"javascript:functionname();\"

The same function works wit

Answer 1

I believe the javascript: prefix is left over from when there were many other script types bouncing around on the web (vbScript, for example) and in order to differentiate between them in HTML you needed to provide these prefixes.

That being said, these tags do absolutely nothing in any browser other then IE anymore, and even in IE you generally can omit them.

Also notice that this entire question is moot since you should be binding event handlers through javascript, not in HTML.