SOURCE

      for (let i = 1; i <= 4; i++) {
          var str = "";
        for (let j = 3; j >= i; j--) {
          str +="\xa0\xa0";
        }
        for (let j = 1; j <= 2 * i - 1; j++) {
          str+='*';
        }
        console.log(str);
      }
      for (let i = 3; i >= 1; i--) {
        var str = "";
        for (let j = 1; j <= 4 - i; j++) {
          str +="\xa0\xa0";
        }
        for (let j = 1; j <= 2 * i - 1; j++) {
          str+='*';
        }
        console.log(str);
      }