JAVASCRIPT

how to convert string to sentence case in javascript

const sentenceCase = () => {
  function firstLetterUpper(string) {
    var newString = string
      .toLowerCase()
      .replace(/(^s*w|[.!?]s*w)/g, function(c) {
        return c.toUpperCase();
      });
    return newString;
  }

  function convertToSentenceCase(string) {
    var newText = firstLetterUpper(string);
    return newText
    }
    convertToSentenceCase();
  };