VID-1972 updating lazy loading module to comply with JS coding conventio...

...ns

Pinging @macbre for code review b/c he's written the majority of this code. 
I think in this case the reason I changed it is because it doesn't matter if this.cache.length is 0, false, undefined, or any other falsy value. In any of those cases we don't want to continue. Also I think the negation is readable.