The code chooses one random image (column) out of a row of images (image columns) and replace it by (insert) the first image out of an array of images of not displayed images. The new image is deleted out of the array and the replaced picture is added at the end of the array.
The paths with ids of the displayed images have to be set initially as well the array with the paths of the not displayed images.
On the amount of image columns the function reacts automatically.
The jquery version adds the fadeOut/fadeIn-method to get smoother transitions.
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