Logging differences in strings in Apps Script

It can be hard to notice where two strings are different in the Apps Script logger. We can borrow JsDiff to help with that.

I’ll be using the cjsDiff library

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You can report on any combination of additions, deletions or no changes. This example does them all.

// compare
  var diffs = cjsDiff.JsDiff.diffChars(
    'quick brown fox jum ove lazy dog', 
    'the quick brown fox jumped over the lazy dog'
  );
  
  
  Logger.log("\n" + diffs.map(function (d) {
    if (!d.removed && !d.added ) {
      return 'no changes--'+d.count + ' chars\n  '+d.value;
    }
    if (d.removed) {
      return 'removed--' + d.count + ' chars\n  '+d.value;
    }
    if (d.added) {
      return 'added--' + d.count + ' chars\n  '+d.value;
    }
	}).join ("\n"));

And the result

added--4 chars
  the 
no changes--19 chars
  quick brown fox jum
added--3 chars
  ped
no changes--4 chars
   ove
added--1 chars
  r
no changes--1 chars
   
added--4 chars
  the 
no changes--8 chars
lazy dog

If that doesn’t quite do it for you, There are various options you can use as documented here

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