check-player-over-dot-in-update-func.js

// there is one number in dots_x for each dot, so dots_x.length is equal to the number of dots.
// For every dot:
for (i = 0; i < dots_x.length; i++)
{
    // if dot's x is same as player's x and dot's y is same as player's y
    if (dots_x[i] == player_x && dots_y[i] == player_y)
    {
        score += 2; // Increment score by two.
    }
}