The simply the best collection of progress bar scripts
The idea is to show the modal and then cause the progress bar to animate from 0% to 100%. Bootstrap already has the transition defined in the framework, you just need to change the width to reflect the progress.
In this tutorial, we support multi-file upload by processing an array of files uploaded by users. The example shows a progress bar to show the uploading progress. Since a multi-file upload takes some time, the progress bar will be helpful to know the status.