A simple brainteaser script that generates an "ASCII" pyramid in console

pyramid.js

function pyramid(rows) {

  var message = []
    , spaces = stars = ''
    ;

  for (var i = 1; i <= rows; i += 1) {

    // The (+1) and (*2) in both equations account for Array.join() omitting the
    //   first (0) index when it concatenates our string

    spaces = new Array(rows-i+1).join('`');
    stars  = new Array((i*2)).join('*');

    message.push(spaces + stars + spaces);
  }

  return message;
}


//    spaces = rows - index
// ---------------------------
//  1 | `````````*
//  2 |         ***
//  3 |        *****
//  4 |       ***** **
//  5 |      ***** ****
//  6 |     ***** ***** *
//  7 |    ***** ***** ***
//  8 |   ***** ***** *****
//  9 |  ***** ***** ***** **
// 10 | ***** ***** ***** ****
// ---------------------------
//    stars = (index * 2) -1


var pyr = pyramid(15);

// render pyramid
console.log(pyr.join('\n'));

// // render diamond
// console.log(pyr.join('\n'));
// console.log(pyr.reverse().slice(1, pyr.length).join('\n'));

// // render inverted pyramid
// console.log(pyr.join('\n'));