Why won't code work without void(0);

Sometimes I visit websites with colorful background, which makes words over it hard to read. So I type the following code in the address bar to solve this problem:

javascript:document.body.style.background='none';

HTML:

But I doesn't work. Therefore I change the code above to:

javascript:document.body.style.background='none';void(0);

HTML:

And now it works. But I don't understand:

1. What's the code void(0); for;
2. Why won't this code work without void(0);.

Any explanation will be appreciated.

 

So the script returns nothing, otherwise you'll lose the current page. You can also include the code into the void:

javascript:void(document.body.style.background='none')