mazetest.js

let arr = [];

function maze (x, y) {
  var n = x * y - 1;
  if (n < 0) { alert('illegal maze dimensions'); return; }
  var horiz = []; for (var j = 0; j < x + 1; j++) horiz[j] = [];
  var verti = []; for (var j = 0; j < y + 1; j++) verti[j] = [];
  var here = [Math.floor(Math.random() * x), Math.floor(Math.random() * y)];
  var path = [here];
  var unvisited = [];
  for (var j = 0; j < x + 2; j++) {
    unvisited[j] = [];
    for (var k = 0; k < y + 1; k++) { unvisited[j].push(j > 0 && j < x + 1 && k > 0 && (j != here[0] + 1 || k != here[1] + 1)); }
  }
  while (n > 0) {
    var potential = [[here[0] + 1, here[1]], [here[0], here[1] + 1],
      [here[0] - 1, here[1]], [here[0], here[1] - 1]];
    var neighbors = [];
    for (var j = 0; j < 4; j++) {
      if (unvisited[potential[j][0] + 1][potential[j][1] + 1]) { neighbors.push(potential[j]); }
    }
    if (neighbors.length) {
      n = n - 1;
      next = neighbors[Math.floor(Math.random() * neighbors.length)];
      unvisited[next[0] + 1][next[1] + 1] = false;
      if (next[0] == here[0]) { horiz[next[0]][(next[1] + here[1] - 1) / 2] = true; } else { verti[(next[0] + here[0] - 1) / 2][next[1]] = true; }
      path.push(here = next);
    } else { here = path.pop(); }
  }
  return ({ x: x, y: y, horiz: horiz, verti: verti });
}

function display (m) {
  var text = [];
  for (var j = 0; j < m.x * 2 + 1; j++) {
    var line = [];
    if (j % 2 == 0) {
      for (var k = 0; k < m.y * 4 + 1; k++) {
        if (k % 4 == 0) { line[k] = '+'; } else
        if (j > 0 && m.verti[j / 2 - 1][Math.floor(k / 4)]) { line[k] = ' '; } else { line[k] = '-'; }
      }
    } else {
      for (var k = 0; k < m.y * 4 + 1; k++) {
        if (k % 4 == 0) {
          if (k > 0 && m.horiz[(j - 1) / 2][k / 4 - 1]) { line[k] = ' '; } else { line[k] = '|'; }
        } else { line[k] = ' '; }
      }
    }
    if (j == 0) line[1] = line[2] = line[3] = ' ';
    if (m.x * 2 - 1 == j) line[4 * m.y] = ' ';
    text.push(line.join('') + '\r\n');
  }
  return text.join('');
}

arr = maze(10, 10);
console.log(display(maze(10, 10)));