javascript - Angular2: Returning Promise

you can create your own promise like this:

var myPromiseFunction = function(iserr){
 var deferred = $q.defer();
 var myreturnvalue = 'somevalue';
 if(iserr === true){
   deferred.reject('some error');
 }else{
   deferred.resolve(myreturnvalue);
 }
 return deferred.promise;
}

And call it like this:

var throwerror = false;
//or var throwerror = true; if you want to create an error
myPromiseFunction(throwerror).then(function(res){
 console.log(res);
}).catch(function(err){
 console.log(err);
})

This way you can create promises (they don't even have to be async but it would not have any purpose for non-async operations.