let numbers = [2, 3, 5, 7, 11, 13, 17];let str = "";let len = numbers.length;for (let i = 0; i < len; i++) { str += (str === "" ? "" : "; ") + numbers[i]; //Do something}//str is "2; 3; 5; 7; 11; 13; 17"console.log(`str is "${str}"`);