If you have a lot of promises in Angular that need to be run sequentially, you can go about it in one of two ways. There is the classic way of chaining callback functions together to achieve the desired result. Or there is the better way, which uses $q.all(). Assume that all of the functions in the example below follow this format:

function promiseX() {
    let deferred = $q.defer();

    ajaxCall().then((response) => {
    }, (error) => {

    return deferred.promise;

Consider the way of callback chaining your promise results.

let values = [];
promiseAlpha().then((val1) => {
    promiseBeta().then((val2) => {
        promiseGamma().then((val3) => {

This, as you can see, is not very pretty at all, and will make it difficult to a) get the resolved value of each promise and use it and b) chain more than a few promises without pulling your hair right out of its sockets. Thankfully there is an alternative in the form of $q.all().

The $q.all() method takes either an object or an array of promises and waits for all of them to resolve() or one of them to reject() and then executes the provided callback function. The values returned from the resolve function are provided depending on the way you give the promises to all().

If you provide them as an array, then the values will be available as an array with the same corresponding order of the promises array. For example:

let promises = [promiseAlpha(), promiseBeta(), promiseGamma()];

$q.all(promises).then((values) => {
    console.log(values[0]); // value alpha
    console.log(values[1]); // value beta
    console.log(values[2]); // value gamma


However if you provide an object literal to all(), the values are attached to an object with the same corresponding property names in the all() callback. I find this way a lot easier because in most (but not all) cases you will have a set number of promises to complete.

let promises = {
    alpha: promiseAlpha(),
    beta: promiseBeta(),
    gamma: promiseGamma()
$q.all(promises).then((values) => {
    console.log(values.alpha); // value alpha
    console.log(values.beta); // value beta
    console.log(values.gamma); // value gamma


This article comes out of a situation where I had to match values against ids from lists returned from an API, where the list data was not preloaded. As you can see, $q.all() becomes a very useful and much shorter way of chaining promise resolve()s than callback chaining.