Extracting numbers from Gmail messages using Google Apps Script

Question

I'm trying to extract numbers such as the ones listed below from my Gmail messages using Google Apps Script.

2,495.00
1,594
3,777.23
642.00

This is the code:

function myFunction() {

  var sheet = SpreadsheetApp.getActiveSheet();
  var threads = GmailApp.search('subject:(Transaction) after:2016/7/31 before:2016/8/10');

  for (var i=0; i<threads.length; i++)
  {
    var messages = threads[i].getMessages();
    var tmp;

    for (var j=0; j<messages.length; j++)
    {
      var content = messages[j].getBody();
      var subject = messages[j].getSubject();
      var date = messages[j].getDate();
      Logger.log(content);

      if (content)
      {
        tmp = content.match(/\d+(,\d+)*(\.\d+(e\d+)?)?/);
        var number = (tmp && tmp[j]) ? tmp[j] : 'No number';
        sheet.appendRow([number, subject, date]);
      }
      else
      {
        sheet.appendRow([content, subject, date]);
      }

    }
  }
}

I've been getting mixed results. For some messages this works as intended but for some it completely skips the numbers from the messages. I'm a newbie to JS/GAS and I thought the problem was in the regex but I'm not sure. Any help in this would be appreciated.

Answer 1

you are facing two trouble here:
the regex you are using don't look optimised (but neither what you are looking is clear a number like 1,594 should not be found if you are also looking at number that look like that 642.00 ). Nevertheless you could use aa regex like Shekhar Khairnar proposed in comment or something similar (the g at the end is important as there is more than one number in your mail).
The second trouble is in the line var number = (tmp && tmp[j]) ? tmp[j] : 'No number'; var number = (tmp && tmp[j]) ? tmp[j] : 'No number'; . Why is there a j var in this line? j is reference to the for loop --> number of messages, nothing to do with the occurences in your message.
What I can propose you is something like that:

function myFunction() {

  var sheet = SpreadsheetApp.getActiveSheet();
  var threads = GmailApp.search('test');
  var re = /(?:\d{1,3}[,])*\d{1,3}\.{0,1}\d{1,3}/g;

  for (var i=0; i<threads.length && i<5; i++) // added a condition because I didn't wanted to have too many results
  {
    var messages = threads[i].getMessages();
    var tmp;

    for (var j=0; j<messages.length; j++)
    {
      var content = messages[j].getPlainBody(); //.getBody();
      var subject = messages[j].getSubject();
      var date = messages[j].getDate();
      //Logger.log(content);

      if (content)
      {
        tmp = content.match(re); // /\d+(,\d+)*(\.\d+(e\d+)?)?/);
        var number = tmp || ['No number']; // result of tmp is either null or an array --> if it's null then it will take the value 'no number'
        Logger.log(number);
        sheet.appendRow([number.join(" | "), subject, date]);
      }
      else
      {
        sheet.appendRow([content, subject, date]);
      }

    }
  }
}