Javascript difficulty, swapping images?

Question

I am using this very simple script (just learning; again) in a button called "next". Now I want to create a button called "previous" and adapt the script into a function "swapBack", but all my guesses have failed. I would really like to keep it supersimple.

function swapImage()
{
   document.slide.src = path[i];
   if(i < path.length - 1) i++; else i = 0;
   onClick("swapImage();");
}

Silent · Accepted Answer

Look at what you're doing right now. You're adding one to the global variable i, so that the next call to swapImage() gets the next image. If that would make i land outside the array, you set it to 0 so it goes back to the beginning.

What you need to do is reverse this process. Instead of adding one, subtract one. If that would make i less than 0, set it to the highest value in the array (path.length - 1) so that it goes back to the end.

Edit:
The way to figure out something like this is not to try random permutations of things, but to examine carefully what you're doing and how it works. These are not just random symbols; they all have specific functions, and if you take the time to read the documentation and learn what those functions are, you'll find this all a lot easier.

That having been said, something like this will do what you want:

if (i >= 0) i--; else i = path.length - 1;

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Javascript difficulty, swapping images?

1 Answer