Function with return value of other function as variable, async or not?

Question

I have the following:

var module = {}
module.setDate = function() {
    var d = new Date();
    return d;
}

Say I now have:

function logDate(){
   var date = module.setDate();
   console.log(date)
   console.log('finished')
}

Is the setting of var date to the return value of module.setDate() synchronous or asynchronous? Could the console ever look like:

undefined
'finished'

_"Could the console ever look like..."_ No, the code posted will always return synchronously. But I feel like perhaps there's more to this question than you're asking? — James Thorpe, Jan 18 '16 at 13:52
Not really tbh, I'm just wanting to use a slightly more complicated version of date setting like the above and was wondering if I could end up with an undefined date in `logDate()`. Thats what I was wanting to know for sure, thanks @Pointy. — OliverJ90, Jan 18 '16 at 13:55

score 0 · Accepted Answer · answered Jan 18 '16 at 13:58

I think you're confusing a function call with a constructor.

var d = new Date();

This will create a Date object immediately, that that's what your function is returning.

On the other hand, if your function were

var module = {}
module.setDate = function() {
    return function() {
        var d = new Date();
        return d;
    }
}

This would be asynchronous, but not parallelly executed. The execution of the function you return would wait until you call the function.

function logDate(){
   var date = module.setDate();
   console.log(date() /* <--- need these parens, now! */)
   console.log('finished')
}

In order to truly execute in parallel, which I think it what you are trying to ask by saying "asynchronous", then I'd suggest reading up on one of these links.

Function with return value of other function as variable, async or not?

1 Answers1