Dynamic Chaining in Javascript Promises

Question

How can I perform dynamic chaining in Javascript Promises, all the time I have seen only hardcoding of the calls for eg., (promise).then(request/funct

Answer 1

I just had a problem with my api provider that doing Promise.all() would end up in concurrency db problems..

The deal with my situation is that i need to get every promise result in order to show some "all ok" or "some got error" alert.

And i don't know why .. this little piece of code who uses reduce when the promises resolved i couldn't get my scope to work (too late to investigate now)

$scope.processArray = function(array) {
    var results = [];
    return array.reduce(function(p, i) {
        return p.then(function() {
            return i.then(function(data) {
                results.push(data);
                return results;
            })
        });
    }, Promise.resolve());
}

So thanks to this post http://hellote.com/dynamic-promise-chains/ I came with this little bastard.. It's not polished but it's working all right.

$scope.recurse = function(promises, promisesLength, results) {

    if (promisesLength === 1) {
        return promises[0].then(function(data){
            results.push(data);
            return results;
        });
    }

    return promises[promisesLength-1].then(function(data) {
        results.push(data);
        return $scope.recurse(promises, promisesLength - 1, results);
    });

}

Then i invoke the function like this:

var recurseFunction = $scope.recurse(promises, promises.length, results);
recurseFunction.then(function (response) { ... });

I hope it helps.