Arvore de Pascal in JavaScript

pascalTree.js

#!/usr/bin/env node
"use strict";

String.PAD_LEFT = 1;
String.PAD_RIGHT = 2;
String.PAD_BOTH = 3;
String.prototype.pad = function(len, pad, dir) {
  var str = this;
  if (typeof(len) == "undefined") { len = 0; }
  if (typeof(pad) == "undefined") { pad = ' '; }
  if (typeof(dir) == "undefined") { dir = String.PAD_RIGHT; }

  if (len + 1 >= str.length) {
    switch (dir){
      case String.PAD_LEFT:
        str = new Array(len + 1 - str.length).join(pad) + str;
        break;
      case String.PAD_BOTH:
        var padlen = len - str.length;
        var right = Math.ceil(padlen / 2);
        var left = padlen - right;
        str = new Array(left+1).join(pad) + str + new Array(right+1).join(pad);
        break;
      default:
        str = str + new Array(len + 1 - str.length).join(pad);
        break;
    }
  }

  return str;
};

String.prototype.repeat = function(n) {
  for (var i=0,s='';i<n;i++,s+=this);
  return s;
};

var pascal = function(n) {
  var triangle = new Array(n);
  var max = 0;

  for (var l = 0; l < n; l++) {
    triangle[l] = new Array(l+1);

    for (var c = 0; c <= l; c++) {
      triangle[l][c] = (c !== 0 && c !== l) ? triangle[l-1][c-1] + triangle[l-1][c] : 1;
      if (triangle[l][c] > max) {
        max = triangle[l][c];
      }
    }
  }

  triangle.min = 1;
  triangle.max = max;
  return triangle;
};

var height = process.argv[2];
if (typeof(height) === 'undefined' || height < 1) {
  process.stderr.write("Please put a valid secund parameter and more than 0.\n");
  process.exit(1);
}

var pascalTree = pascal(height);

// print
var block = pascalTree.max.toString().length + 1;
var lastLine;

for (var i = 0; i < pascalTree.length; i++) {
  lastLine = '';
  for (var j=0; j < pascalTree[i].length; j++) {
    lastLine += pascalTree[i][j]
                .toString()
                .pad(block, ' ', String.PAD_BOTH);
  }

  process.stdout.write(lastLine.pad(block * height, ' ', String.PAD_BOTH) + "\n");
}

var trunk = '#'.repeat(height & 1 ? height : height-1)
               .pad(lastLine.length, ' ', String.PAD_BOTH) +
            "\n";

process.stdout.write(trunk.repeat(Math.ceil(height / 2)));