JavaScript How ethical to use Javascript libraries that are available on the net?

I want to do something with JavaScript on my website but don't know how to implement it, but i've found it has already been written by someone and is available to download free as they've put it on net.
So is it right morally to use something that someone has already been written? does this count as cheating? does it infringe any copyrigh

 

Check to see if there's a copyright notice or licence agreement. In the absence of either my interpretation of the situation would be that the owner of the work wouldn't have made it available on the Internet if he/she didn't want others to make use of it. Contact the person and ask for permission if you're unsure.

You'll have to make your own judgement as to what's morally acceptable where there's uncertainty but I'd say there are three levels of trangression in this area.

At the lowest level making use of other people (either their code or their advice) is commonplace.

Passing someone else's work off as your own is more serious - probably illegal and wrong in most people's view.

Rebranding someone else's product as your own and exploiting it commercially could get you into big trouble.

In your situation, to ease your conscience, give credit to the originator either in your code (for the benefit of other programmers that might look at it) or in the product itself.