Fit all the <p> inside a div

[ArtemisGraphic]

Is it possible to fit all the p elements inside a div?
I have a div with fixed width and height 300px and 600px, with many p elements inside, I tried with textFit(document.querySelectorAll(".box" + "p")); but nothing changes.
If I remove p tags and just do textFit(document.querySelectorAll(".box")); it works, but I really need paragraphs.
Any way to do this?

[MattiJarvinen]

Try:
textFit(document.querySelectorAll(".box + p"))

[ArtemisGraphic]

I tried but it doesn't work, I get no errors though. It works with just textFit(document.querySelectorAll(".box")) if I remove the p tag, but I really need p.