替换第n次出现的javascript

function replaceNthOccurrence(str, search, replace, n) {
  var regex = new RegExp(search, 'g');
  var match;
  var count = 0;

  while ((match = regex.exec(str)) !== null) {
    count++;

    if (count === n) {
      var startIndex = match.index;
      var endIndex = startIndex + match[0].length;
      var replacedStr = str.substring(0, startIndex) + replace + str.substring(endIndex);
      return replacedStr;
    }
  }

  return str;
}

var originalStr = "This is a JavaScript example. JavaScript is a popular programming language.";
var searchStr = "JavaScript";
var replaceStr = "TypeScript";
var occurrence = 2;

var replacedStr = replaceNthOccurrence(originalStr, searchStr, replaceStr, occurrence);
console.log(replacedStr);