Promise.join

Promise.join(
    Promise<any>|any values...,
    function handler
) -> Promise

For coordinating multiple concurrent discrete promises. While .all is good for handling a dynamically sized list of uniform promises, Promise.join is much easier (and more performant) to use when you have a fixed amount of discrete promises that you want to coordinate concurrently. The final parameter, handler function, will be invoked with the result values of all of the fufilled promises. For example:

var Promise = require("bluebird");
var join = Promise.join;

join(getPictures(), getComments(), getTweets(),
    function(pictures, comments, tweets) {
    console.log("in total: " + pictures.length + comments.length + tweets.length);
});

var Promise = require("bluebird");
var fs = Promise.promisifyAll(require("fs"));
var pg = require("pg");
Promise.promisifyAll(pg, {
    filter: function(methodName) {
        return methodName === "connect"
    },
    multiArgs: true
});
// Promisify rest of pg normally
Promise.promisifyAll(pg);
var join = Promise.join;
var connectionString = "postgres://username:password@localhost/database";

var fContents = fs.readFileAsync("file.txt", "utf8");
var fStat = fs.statAsync("file.txt");
var fSqlClient = pg.connectAsync(connectionString).spread(function(client, done) {
    client.close = done;
    return client;
});

join(fContents, fStat, fSqlClient, function(contents, stat, sqlClient) {
    var query = "                                                              \
        INSERT INTO files (byteSize, contents)                                 \
        VALUES ($1, $2)                                                        \
    ";
   return sqlClient.queryAsync(query, [stat.size, contents]).thenReturn(query);
})
.then(function(query) {
    console.log("Successfully ran the Query: " + query);
})
.finally(function() {
    // This is why you want to use Promise.using for resource management
    if (fSqlClient.isFulfilled()) {
        fSqlClient.value().close();
    }
});

Note: In 1.x and 0.x Promise.join used to be a Promise.all that took the values in as arguments instead of an array. This behavior has been deprecated but is still supported partially - when the last argument is an immediate function value the new semantics will apply