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 | var str = 'cbdefdfpoweqwlkjsaaaaz'function findMostLetter(str) {
 
 let match = str
 .replace(" ", "")
 .split("")
 .sort()
 .join("")
 .match(/(\w)\1*/g);
 let res = "";
 let len = 0;
 match.forEach((val, key) => {
 if (val.length > len) {
 res = val[0];
 len = val.length;
 }
 });
 return res;
 }
 
 findMostLetter(str)
 
 |