JavaScript string manipulation with certain logic in it
Minor upgrades, nice idea for the prepop result Raynos

result = ["0 0"]; // Outside of loop

// ...

if (is2PixelRatio) width /= 2;   
width += 10; // [Insert magik number explanation here]

result.push(  -(i * width) + "px 0"  ); // Negative numbers will convert to "-30"