JS to find the most frequently-seen characters in a string

I have seen such a pen question before, and I have worked it out in the traditional way. I have nothing to worry about and think about it. I suddenly got inspiration. The idea is as follows:

1. sort the strings using the sort method of the array so that all the same letters can go together.

2. Use a regular expression to match two adjacent different characters with a comma in the middle

3. Split the strings obtained in step 2 into Arrays Using commas as the bounds.

4. Sort the array by string length. The first element obtained is the answer.

The Code is as follows (Thank you very much for reminding me that the regular expression has been corrected)

String. count = function (str) {var ret = str. split (""). sort (). join (""). replace (/((.) \ 2 *)/g, "$1 ,"). split (","). sort (function (a, B) {return B. length-a.length}); return [ret [0] [0], ret [0]. length];} var s = "& (& $ # (jflsdjfoiwefdjsklfewosd2316907345asdsdwsdqs"; alert (String. count (s ));

The returned value is ['s', 6].

The problem is that the regular expression is not well written, and a comma is added at the end of the string. Then, the last element of the ret array is a null string. if you have any good solutions, please contact us.