Often it doesn’t matter when a Promise returns data and the members of a collection of Promises can be resolved independently without regard to timing. A function can perform asynchronous tasks that don’t depend on the data from, or the success of, other asynchronous tasks.
But sometimes business rules or program design require that asynchronous actions are dependent on other asynchronous operations. For example...
Are you a developer looking for a new hobby that’s compatible with sheltering in place? Would you like to be able to share it with friends from a virus-safe distance?
You can stargaze from the safety of your own lawn, balcony, or roof, and you don’t need any equipment other than your own eyes, and maybe a pair of binoculars. There are plenty of bright objects in the night sky that are visible with the naked eye. One of them is the International Space Station (ISS), which is the third brightest object in the sky after the sun and moon.
The ISS whips around the earth at 27,576 kilometers per hour (17,000 miles per hour), making a complete orbit every 94 minutes. Opportunities to observe it only last a few minutes, so it’s helpful to know when the ISS will be visible and from which direction it will appear.
SMS messages can reach over 4.5 billion text-enabled devices to notify people about upcoming appointments, emergencies, traffic disruptions, or commercial promotions. Sending SMS messages programmatically enables you to reach many people almost simultaneously. With Twilio Programmable SMS you can create a Node.js application that sends many messages and reports when each of them has been delivered—or not.
You can create a mechanism for monitoring and reporting the status...
This post focuses on how to utilize RxJS Observables with REST API calls...
You can put these skills together to retrieve remote data through an HTTP request and work with the call response asynchronously. But in doing so you’ll probably notice that code has at least one pitfall: the logical order of declared functions is reversed. That makes the code hard to read and maintain.
Promises can also be chained together to use the state of settled promises (resolved or rejected) and the promises’ values to control the flow of execution in your program. This is useful when you have a sequence of asynchronous operations to perform that each depend on the results of the previous operation: the next step in the chain isn’t performed until the preceding step is resolved. Chains of promises also include error propagation; errors in a...
As an old programming saying goes:
"Any fool can write code that a computer can understand. Good programmers write code that humans can understand."
The first part of this...
In many applications you'll also want to limit access to some data and functions to particular users. While you could do this directly in your service APIs, there's a better way.
This post will show you how to add two-factor authentication (2FA) with Twilio Authy and an authorization web service using JSON Web Tokens (JWTs), a standard for securely storing and transmitting sensitive data.
This post will show you how to integrate service discovery and intelligent routing into a Node.js application built with a microservices architecture. You'll see how you can do this with two Netflix open source projects, Eureka and Zuul, that run in the Java SE Runtime Environment.
The Netflix Eureka server provides service discovery. This gives your application's services the ability to find other services without knowing where they are hosted or the full URL required to reach them, so you don't have to provide complete URLs...
Applications are built from pieces, like packages and modules, but at some point those structures aren’t enough to reduce the size and complexity of the application. The idea behind distributed systems is to break big, monolithic designs into small, independent programs which communicate with each other to exchange data and perform operations.
One of the many variants of distributed systems is the microservices architecture, which structures an application as a collection of loosely coupled services. Services are fine-grained and the communication protocols are lightweight (like the HTTP protocol).
Cookies are a ubiquitous feature of web applications, as anyone clicking GDPR notifications for the last several months has realized. Securely handling the data in those cookies is just as much a requirement as the consent notification. Encrypting your Angular and Node.js application cookies is a way to prevent unauthorized access to confidential and personal information, and it’s easy to implement.
As you know, using an httpOnly cookie helps prevent cross-site scripting (XSS) attacks. (You can learn more in another post.) But what about protecting one registered user’s data against another registered user? Are cookies vulnerable to attacks from trusted users?
This post will demonstrate how authenticated users can get unauthorized access to other users’ cookie data. It will also show you how to encrypt your cookies so the data can only be read by your code, not by users.
Two-Factor Authentication (2FA) provides web applications with an important additional layer of security, but 2FA requires the user to perform an additional action each time they log in. This extra step can be wearying for users who sign into an application frequently. Is it possible to maintain the security provided by a second factor while making an application convenient for repeat visitors? It is with Angular, Node.js, and Twilio Authy.
Implementing a “remember me” checkbox on the login page is a convenient way for a user to indicate they are going to be a repeat visitor. Behind the scenes, an encrypted security cookie is a convenient mechanism for identifying a user who has previously checked the “remember me” box and logged in successfully from a specific machine.
With Twilio Authy and an encrypted cookie, such as a JSON Web Token (JWT), you can make the sign-in process fast and...
Having a shared codebase for both the server-side and browser-side code of an Angular application aids the maintainability of a project. You can do that with Angular Universal and Node.js using the server-side rendering (SSR) concept. You can even use SSR to securely pass data, including files, between the application server (Node.js) and the Angular application running on it.
This post will show you how to create an application for uploading, storing, managing, and downloading files from a Node.js server using a single codebase. When you finish this project you’ll be able to...
User authentication is a crucial requirement for many Angular applications and simply logging in with user ID and password is increasingly inadequate security. Two-Factor Authentication (2FA) provides device-based security that is substantially more difficult to hack, but building your own 2FA system is a daunting challenge. Twilio Authy makes it easy to add 2FA to Angular apps.
This post will show you how to add Authy to your Angular project. You’ll also learn how to improve the user’s experience and your app’s security by using Angular Universal to implement the login process.
Search Engine Optimization (SEO) is vital for most web applications. You can build SEO-friendly Angular apps with Angular Universal, but what about the performance and efficiency of such an application? This post will show you how to build fast Angular apps that use client and server resources efficiency while providing server-side rendering (SSR) for SEO purposes.
In this post we will...
Search Engine Optimization (SEO) is important for many Angular single-page applications (SPAs). You can build SEO-friendly Angular websites with Angular Universal, but how do you make your app SEO-friendly in every language your website supports? Google, Yandex, and Baidu, might request your pages in English, Spanish, Russian, or Chinese: how do you make your server-side rendering return the correct language?
The answer is ngx-translate, the internationalization (i18n) and localization library for Angular. This module makes it easy to use translation files that provide the correct language for both client-side and server-side rendering. This post will show you how to use it.
You can build search-engine optimized (SEO) friendly single page applications (SPA’s) with Angular Universal, a technology that runs your Angular application on the server. And you can reduce the cost of running those applications with AWS Lambda, an event-driven, serverless computing platform provided as a part of Amazon Web Services (AWS). This post will show you how to build and deploy Angular Universal projects on AWS Lambda using Serverless Framework, an open-source command line interface for building and deploying serverless applications.
A memory leak is one of the worst types of issues you can have. It’s hard to find, hard to debug, and often hard to solve. Unfortunately, this problem occurs in every programming language or framework, including Angular. Observables are awesome, because of the incessant stream of data, but this benefaction can cause serious problem with memory leak. Today we will take a closer look at the ngOnDestroy Angular hook, and answer the question: “When should I unsubscribe from an observable? What is the best pattern to use?”
Routing is an essential concept in Single Page Applications (SPA). When your application is divided into separated logical sections, and all of them are under their own URL, your users can easily share links among each other.
In my previous post, Building an App from Scratch with Angular and Webpack, I covered how to start working with Angular and Webpack. Today we will take a closer look at implementing more components and navigating between them.
Using Angular CLI is a popular way of creating Single Page Apps (SPA) with Angular. However, sometimes CLI is not an option for your project or you just want to have better control on what’s going on behind the scenes. Let’s take a look at how we can create an Angular project entirely from scratch.
The Serverless framework makes it easy to deploy applications to AWS Lambda. However, Serverless does not currently support binary files, but we can solve this issue by implementing a Serverless plugin and uploading proper configuration to the AWS API Gateway.
Functions-as-a-Service (FaaS) such as Amazon Web Services Lambda and Twilio Functions can be cheap execution environments in which you pay only for resources used to deal with a particular request, typically measured in seconds or milliseconds.