Somewhat off-topic here, because the question is about web based solutions, but if you ever need to implement a progress bar on the command line, use Smart::Comments:

    use Smart::Comments;

    for my $j (1..500) {      ### Compiling===[%]  done
        select undef, undef, undef, 0.01;
    }
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Note that the entire progress bar code is hidden in the special ### comment.