Setting a max text size, but shrinks when needed

Hello,

I'm building a simple form that has a few text boxes. I need the boxes to have a max text font size of 6. However, I need that size to shrink if the user inputs more text than the box size. I don't have room for wrapping or multiple lines. I found an answer on this form via google that told me to do the following

Properties...

Options

• no Multiline, Chars Limit, Comb AND Allow Rich Text

Actions

• OnFocus | Run JavaScript

add this code:

event.target.textSize = 0;

• OnBlur | Run JavaScript

add this code:

var len = event.target.value.toString().length;
//console.println("LEN " + len);
if (len < 4) {
    event.target.textSize = 18;
}
else {
    event.target.textSize = 0;
}

Ref: https://answers.acrobatusers.com/Is-it-possible-to-set-minimum-and-maximum-font-sizes-in-Acrobat-PDF-form-fields-q110082.aspx

However, when I attempt to use this code (but with text size set to 6) it will work the first time text is entered. However, If I erase some text and try to put anything else in, the text will go bigger than 6 point. It goes back to "auto" text size. The JavaScript only seems to work one time. I'm pretty new to using JavaScripts. What am I doing wrong? Any help is appreciated.

I'm using Adobe Acrobat Pro DC