JS not working properly in IE and Edge browsers

Hello!
I've got a small JS-based music player on my homepage in its upper-left corner (just above the logo). And it works fine in all browsers, except IE and Edge. In those it shows NaN where the song's total time is supposed to be after the page loads. I can't attach a print-screen here, but you can either follow my site's link or here is a link to a photo-bank where it's been uploaded successfully.
https://ift.tt/2OrtLvY
But if you try to load my site in FF or Chrome, then...

JS not working properly in IE and Edge browsers

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