simple_language_on_JavaScript.js

"use strict";

var program = `d m 100 100 u m 100 0 d m 200 100`;

var x = 0, y = 0, raised = true;
var words = program.match(/\w+/g);
for (var i = 0; i < words.length; i++) {
  if (words[i].toUpperCase() == 'D') raised = false;
  if (words[i].toUpperCase() == 'U') raised = true;
  if (words[i].toUpperCase() == 'M') {
    var nx = parseInt(words[++i]), ny = parseInt(words[++i]);
    if (!raised) {
      var ctx = document.getElementById("c").getContext('2d');
      ctx.beginPath();
      ctx.moveTo(x, y);
      ctx.lineTo(nx, ny);
      ctx.stroke();
    }
    x = nx; y = ny;
  }
}