Including code with JS

[DaveMania]

Basic question with probably a deep answer. I've been planning on buying myself some Javascript books but not gotten round to it.

How does one include code from a file using javascript? (I know i'm not explaining it very well).

for example: Adsense, Shoutmix.

[ScriptFlipper]

http://www.google.com/search?q=javascript+src

[nathan99]

do u mean including a JS script? or wat