pyramid.js

// iterative solution



function pyramid(n) {
  const midPoint = Math.floor((2 * n - 1) / 2);

  for (let row = 0; row < n; row++) {
    let level = "";
    for (let column = 0; column < n * 2 - 1; column++) {
      if (midPoint - row <= column && midPoint + row >= column) {
        level += "#";
      } else {
        level += " ";
      }
    }
    console.log(level);
  }
}

pyramid(4)  //     #
                  ###
                 #####
                ####### 
                
               
// recursive solution 
function pyramid(n, row = 0, level = "") {
  if (row === n) {
    return;
  }

  if (level.length === n * 2 - 1) {
    console.log(level);
    return pyramid(n, row + 1);
  }
  const midPoint = Math.floor((2 * n - 1) / 2);
  let add;

  if (midPoint - row <= level.length && midPoint + row >= level.length) {
    add = "#";
  } else {
    add = " ";
  }
  return pyramid(n, row, level + add);
}       

pyramid(4)  //     #
                  ###
                 #####
                #######