Asynchronous stack (LIFO)

astack.js

"use strict";

var stack = (function(){

    function _stack(){
        this.stack = [];
        this.queue = [];
    };

    _stack.prototype.push = function stack_push(data){
        var me = this;
        if (me.queue.length) {
            me.queue.shift()(data);
        } else {
            me.stack.push(data);
        }
    };

    _stack.prototype.pop = function stack_pop(){
        var me = this;
        if (me.stack.length) {
            return Promise.resolve(me.stack.pop());
        } else {
            return new Promise(function(resolve, reject){
                me.queue.push(function(data){
                    resolve(data);
                });
            });
        };
    };
    return _stack;
})();

// Example:
// var s = new stack();
// s.push("hello");
// s.pop().then(function(data){console.log(data)});
// s.pop().then(function(data){console.log(data)});
// s.push("world");