Fit texts in textbox by resizing font size using after effects expression

there may be a better way, but this had worked for a smaller task of mine. feel free to change the text increment values to whatever text you plan on using. if youre using larger text, then .5 may be too small of an increment.

/*do this to whatever textframe you want to check. but as long as the text frame is returning true for overset, the loop will keep running and each loop will reduce each character by .5 size and .5 leading.*/
while(CheckIfOverset(Selection)){
        var CharLen = Selection.textRange.characters.length
        for (var p = 0; p < CharLen; p++) {
            Selection.textRange.characters[p].size-=0.5
            Selection.textRange.characters[p].leading-=0.5
        }
    }

/* overset function takes area frame, converts to point text and determines if text is overset */
function CheckIfOverset(t) {
    var d;
    d = t.duplicate()
    d.name = 'temp'
    d.convertAreaObjectToPointObject()
    d = t.parent.textFrames['temp']
    if (d.contents.replace(/[\x03\r]/g, '') !== t.contents.replace(/[\x03\r]/g, '')) {
        d.remove();
        return true
    } else {
        d.remove();
        return false
    }
}