So I have a localStorage variable, say 100. 

Then a JSON encoded array called localStorage.completed which is: ["44", "33", "18"] 

What I want to do is generate a random number between 0-100 excluding the ones in the completed array. Just wondering what the easiest and most efficient way to write the code would be? Mine looks like spaghetti at the moment, the lead developer is away so I am taking charge… don't want to mess up his perfect code as he is a tad OCD. 

Thankyou :)