opening "js" use script

(1) <script type="text/javascript" src="javascript.js"></script>

(2) <script language=JavaScript src="javascript.js"></script>

(3) <script src="javascript.js"></script>


Is (1) the best way?

yes 1 is the best way.
2 is the old way and some browsers may not recognize it.
3 does not specify what kind of script you are using even though you refrence the src to a javascript file.