es6.js

'use strict';
// Block Coordinate System
// Starts from the bottom left. All values are positive. 0,0 is 1 block
// 
// Shape order is clockwise starting from the top.
var tetrominoShapes = { 
  // I Block
  0: [
    [1,0, 1,1, 1,2, 1,3],
    [],
    [],
    [],
  ]
}

class Tetromino {
 
  constructor(type) {
    
    if ( ( isNaN(parseFloat(type)) && ! isFinite(type)) || type > 6 ) {
      this.randomize();
    } else {
      this.type = type;
    }
    
  }

  randomize() {
    this.type = Math.floor( Math.random() * 7 );
  }

}

var Tetris = class {
  constructor() {
    this.xyz = 'TETRIS!';
  }
}


var currentTetromino = new Tetromino(7);
var nextTetrominoes = [];

for (let i = 0; i < 6; i++) {
  nextTetrominoes.push( new Tetromino() );
}

console.log(currentTetromino.type);
console.log(nextTetrominoes);

console.log(Tetris);