Pyramid array builder
When writing a simple function to return something if something is true or return something else, you should probably only have one return statement in the function.

increasing the amount of returns in a function makes the function less readable and more prone to mistakes.  if you only need one return statement, then only use one return statement.

Personally I would write this


public getBlanco(){
  if(this.array.length){
    return this.array[1][0];
  }
  return null;
}



like this instead

public getBlanco(){
    return this.array.length ? this.array[1][0] : null;
}


using a ternary is really the cleaner way to do this because you are really saying

if there are items in the array
    return item [1][0]
else
    return null