Finding text (multiple times) and highlighting

Question

I would like to find all the instances of a word in a Google doc and highlight them (or comment - anything so it stands out). I have created the following function, but it o

Answer 1

Ok so, chaining your codes it could finish like this :

function findWordsAndHighlight() {
var doc = DocumentApp.openById("DocID");
var text = doc.editAsText();
var search = "searchTerm";
var index = -1;
var color ="#2577ba";
var textLength = search.length-1;

while(true)
 {
   index = text.getText().indexOf(search,index+1);
   if(index == -1)
     break;
   else text.setForegroundColor(index, index+textLength,color );
 }

};

I still have a doubt. This code works nice, but why I have to use search.length-1?