I have 2 promises that takes in input 2 differents parameters:
promise1(var1)
promise2(var2)
These promises runs in parallel inside a Promise.all():
Promise.all([promise1(var1), promise2(var2)])
Sometimes, depending on the value of var1 or var2, I just need one of them to be executed. For example, if var1 is null, I just want
Promise.all([promise2(var2)])
Or, if var2 is null:
Promise.all([promise1(var1)])
Is there an elegant way to code this situation without if, else branches?
it can be done with dynamically create promise.all array argument.
var promises=[];
if(var1==null)
promise.push(promise2(var2));
if(var2==null)
promise.push(promise1(var1));
Promise.all(promises);
Why do you think if .. else is not elegant? In many situation it's the most readable code and thus IMHO is better than some "well-constructed" oneliner, which you won't understand anymore the next time you are reading it.
I personally would make an array and push the various promises into that array based on the conditions. And then finally make a Promise.all with this array. IMO this is the most readable and elegant way to do this.
let promises = [];
if (val1) promises.push(promise1(val1));
if (val2) promises.push(promise1(val2));
Promise.all(promises);
Promise.all([
var1 ? promise1(var1) : Promise.resolve(null),
var2 ? promise2(var2) : Promise.resolve(null),
]);