[jQuery] contradictory between jquery and pure javascript

Hi all, my site is jquery based but i used a javascript code in a
separate file to create a marquee, my problem now is that they don't
work together, if i called only the jquery, it works, and if i called
only my own javascript file it works, but calling the both together,
only the last one called works, do
such a contradictory problems appear frequently, solution please.