Finding top three most occurring words in a string of text in JavaScript

Problem

We are required to write a JavaScript function that takes in a English alphabet string. Our function should return the top three most frequent words present in the string.

Example

Following is the code −

const str = 'Python was developed by Guido van Rossum in the late eighties and early nineties at the National Research Institute for Mathematics and Computer Science in the Netherlands. Python is derived from many other languages, including ABC, Modula-3, C, C++, Algol-68, SmallTalk, and Unix shell and other scripting languages. Python is copyrighted. Python source code is now available under the GNU General Public License (GPL)';
const findTopThree = (str = '') => {
   str = str
   .replace(/[^\w\s]|_/g, "")
   .replace(/\s+/g, " ")
   .toLowerCase();
   const arr = str.split(' ');
   const map = {};
   arr.forEach(word => {
      map[word] = (map[word] || 0) + 1;
   });
   const res = Array.from(Object.keys(map), key => [key, map[key]]);
   res.sort((a, b) => b[1] - a[1]);
   return [res[0][0], res[1][0], res[2][0]];
};
console.log(findTopThree(str));

Output

Following is the console output −

["python","the","and"]