converting a hex string to uint32 in JS context

[JohnAD]

Sadly, this did lead to an odd JS bug. I'll look into posting in a `issue`.
    
    
    var mask = 0x80000000'u32
    if mask == (mask and mask):
        echo "good"
    else:
        echo "not good"
    
    
    Run

One gets different results based on compiler target. I suspect the lack of 
integrated "unsigned int" support in JS itself is causing it to not like the 
high bit being set on an `and`. But that is just a guess on my part.