Question

I am practicing some various JavaScript techniques, namely function properties. Here is something that has me scratching my head a little.

//property of the q0 function
q0.unique = 0;


function q0() {

return q0.unique++;

}

console.log(q0()); //returns 0 
console.log(q0()); //returns 1
console.log(q0()); //returns 2
console.log(q0()); //returns 3

Shouldn’t the first call to the function return 1? Why is it returning 0? q0.unique is already set to 0?

Answer 1

That would be true if your code was:

function q0() {

return ++q0.unique;

}

The suffixed ++ returns the current value then increments. With a prefixed ++ it’s the other way around.