Sheets: indexOf not finding substring

Question

Working in apps script I have :

var conversations = row['CONVERSATION'].split('|');
var replies = conversations.map(function(message) { //ONLY CHECKED ROWS.
  var m = message.toString();
  return m.indexOf('R:')==true;
});  

    Logger.log(conversations);
    Logger.log(replies);

When I look at the logs:

[19-03-08 11:51:12:892 EST] [R: test3 ,  R: test3 ,  tx]
[19-03-08 11:51:12:893 EST] [false, true, false]

Why is the first element in the replies array false. Shouldn't it be true?

Answer 1

Why is the first element in the replies array false. Shouldn't it be true?

So if the indexOf matches first element you get index as 0 and your condition is checking for true values but 0 is not so it is returning you false.

This will fail if your matched index is 0

m.indexOf('R:') === true 

Better you just check

m.indexOf('R:') !== -1

Ref: String.prototype.indexOf