futurePromise.js

function futurePromise() {
    var _resolve = null;
    var _reject = null;

    this.promise = new Promise(function(resolve, reject) {
        _resolve = resolve;
        _reject = reject;
    });
    this.then = function() {
        return this.promise.then(...arguments);
    }
    this.catch = function() {
        return this.promise.catch(...arguments);
    }
    this.resolve = function() {
        _resolve(...arguments);
    }
    this.reject = function() {
        _reject(...arguments);
    }
}

// create a promise
var p = new futurePromise();

// wait for it (multiple times if needed)
p.then(val => {
    console.log('val(1)', val);
})

// wait another time and chain
p.then(val => {
    console.log('val(2)', val);
    return new Promise(res => {
        setTimeout(_ => { res(); }, 1000)
    }) })
 .then(val => {
    console.log('.then(somethingElse)')
 })
 .catch(err => { console.error('err', err); })

// resolve it whenever you want
setTimeout(() => {
    p.resolve({value:true});
}, 1000)