How to batch underline all text in all pdf files in a folder ?

Only want to underline or strike through searched text in files. I found a code online but its on color highlighting.

I am looking for something similar to this:i

// I copied it from somewhere online

// Highlight Color

var colHilite = color.yellow;

var oDoc = event.target;

var aAnnts = oDoc.getAnnots({sortBy:"Author"});

for(var i=0;i<aAnnts.length;i++)

{

   if(aAnnts.type == "Redact")

   {

      aAnnts.type = "Highlight";

      aAnnts.strokeColor = colHilite;

   }

}