Working with promises inside an if/else

Question

I have a conditional statement in which I need to perform one of two operations, then continue after whichever operation has resolved. So my code currently looks as follows:

Answer 1

The way I would do it would be to put the if check into another function that returns a promise. The promise gets resolved with the resolve of the other function calls in the if-else statement.

Example:

function performCheck(condition) {
    var defer = $q.defer();
    if (condition) {
        doThingA().then(function(response) {
            defer.resolve(response);
        });
    } else {
        doThingB().then(function(response) {
            defer.resolve(response)
        });
    }
    return defer.promise;
}
performCheck(condition).then(function(response) {
    //Do more code.
});

In my opinion, I would prefer this method because this function can now be used in multiple places where you have a check on the condition, reducing code duplication, and it is easier to follow.

You could reduce this down further with

function performCheck(condition) {
    var defer = $q.defer();
    var doThisThing = condition ? doThingA : doThingB;
    doThisThing().then(function (response) {
        defer.resolve(response);
    });
    return defer.promise;
}
performCheck(condition).then(function(response) {
    //Do more code.
});