Possible case sensitivity "bug"

[tunelessly]

Hello,

I'm developing an app that uses this library. I think I found a possible bug, or at the very least, a surprising (to me) behavior.

When computing the distance between two strings in case-insensitive mode, the highest match in my data set doesn't match what I expected. I looked at the code and the "problem" happens here - the inputs are being compared without regard for the user's selected settings.

Example

I've provided an example here - typescript playground.

Actual Behavior

jaroWinkler("haka", "Shakasi", {caseSensitive: false}); // ~0.857
jaroWinkler("haka", "Hakatiz", {caseSensitive: false}); // ~0.857 Expected this one to be equal to ~0.91
                                                        // since the prefixes match in case insensitive mode

Expected Behavior

jaroWinkler("haka", "Shakasi", {caseSensitive: false}); // ~0.857
jaroWinkler("haka", "Hakatiz", {caseSensitive: false}); // ~0.91

Workaround

Converting the strings to upper/lowercase ourselves avoids the issue entirely and results in the expected behavior:

jaroWinkler("haka", "Shakasi".toLowerCase()); // ~0.857
jaroWinkler("haka", "Hakatiz".toLowerCase()); // ~0.91

Potential "fix"

Before the loop in line 95, add the very same check that's present in the jaro function:

  if (options && !options.caseSensitive) {
    str1 = str1.toUpperCase();
    str2 = str2.toUpperCase();
  }