You might remember locking from your undergrad systems programming class. Locks help when multiple threads that can be interrupted at any time access a shared resource. In distributed programming (like building a Node.js server that talks to a database) you have a similar problem: parallel operations can mutate documents in the database in conflicting ways. In particular, enforcing uniqueness, such as making sure only one user has a given email, is tricky.

Mongoose setters have always had the limitation that they only work for save(), not for queries. For example, let's say you have a schema that enforces your emails are always lowercase:

One great perk of async/await in Node.js is how well it integrates with existing libraries. By now, most popular Node.js libraries support some sort of promise-based API, so they integrate nicely with async/await. You might even have the pleasure of removing a few dependencies from your package.json if you start using async/await instead of co. In this article, I'll show you how async/await works with mocha tests, express routes and middleware, and mongoose queries and cursors.

Mongoose 4.10.0 just landed and brings with it several powerful features and bug fixes. The most +1-ed feature in this supporting unique in array definitions via the mongoose-unique-array plugin. This feature is implemented as a separate plugin because mongoose-unique-array does much more than simply create a unique index, it also ties in to validators and versioning. In this article, I'll explain how to use mongoose-unique-array and the caveats you need to be aware of when using it.

I've been looking at PubNub as a potential alternative to Firebase for push notifications. At a high level, PubNub is pubsub-as-a-service: once you plug in PubNub's JavaScript library, you can start publishing messages and subscribing to channels without having to deploy Kafka, ZeroMQ, etc.

pkg is Zeit's (the company behind Next.js) new tool for bundling Node.js projects into standalone binary executables. A standalone executable has numerous advantages: as long as you're on a compatible OS, you can run the executable without installing Node.js, docker, or any other runtime. You can ship your executable to a vanilla EC2 instance and run it without any extra setup, no need to maintain AMIs or use Packer. You can also cross-compile with pkg, so you can build an OSX-compatible executable on your Linux box and vice-versa. In other words, pkg gives you the best parts of Golang in Node.js.

Next.js is a powerful framework for building server-side rendered applications. Next.js is just a wrapper around React, but it abstracts away all the ugly bits of React: build systems, transpilation, routing, CSS, etc. Most importantly, it makes server-side rendering with React dead simple, no need to carefully structure your code for use with preact-render-to-string or figure out the lastChild pattern for replacing the server-side rendered component with the client-side rendered component. In this article, I'll show you how to build a basic Next.js app with server-side rendering on top of an Express and MongoDB API.

Async/await makes it easy to integrate asynchronous behavior with imperative constructs like for loops, if statements, and try/catch blocks. Unfortunately, it doesn't do the same for functional constructs like forEach, map, reduce, and filter. Using these constructs with async functions leads to behavior that can seem downright baffling. In this article, I'll show you some common gotchas for async functions with JavaScript's built-in functional array methods and how to work around them.

Firebase is a great tool for getting data from a server to a client. Firebase handles caching, retries, socket management, and all the other unpleasant details of getting data to a client with spotty internet connection. In particular, Firebase is excellent for mobile web and mobile apps. In this article, I'll walk you through using Firebase with Preact, a lightweight React alternative, to build a simple app with server-side rendering.

Node.js 6.6.0 added a sporadically useful bug/feature: logging unhandled promise rejections to the console by default. In other words, the below script will print an error to the console:

By virtue of the event loop, scheduling tasks in Node.js is relatively straightforward. Plain old setTimeout() and setInterval() are sufficient for many basic use cases where you would normally use cron. However, things get more interesting when you need durable transactional scheduling, for use cases like:

I find the existence of tools like nvm baffling. I could understand if setting up Node.js required an actual installer or compiler or python, but node has pre-built binaries for most operating systems. Node and npm are both portable standalone executables, so all you need is the right binary for your OS in the right place on your file system. Especially if you're switching back and forth between Node 6.x and 7.6.0 for async/await, you should simplify your node version management workflow rather than using yet another bloated tool.

Async/await in Node.js opens up a host of powerful design patterns. Tasks that used to take complex libraries or intricate promise chaining can now be done with rudimentary if statements and for loops. I already wrote about these kind of design patterns with co, but async/await makes these patterns accessible in vanilla Node.js, no outside libraries required.

Arguably the biggest new feature in Node.js 7.6.0 is that the much awaited async function keyword is now available without a flag. Callback hell and promise hell are now in the past. But, like Uncle Ben always reminded us, with great power comes great responsibility, and async/await gives you a lot of new and exciting ways to shoot yourself in the foot. You still need to handle errors and be aware of the async nature of your code, otherwise you'll inevitably be complaining about "async/await hell" in 6 months.

WebAssembly is an exciting new language that many JavaScript engines have added support for. WebAssembly promises to make it much easier to compile languages like C and C++ to something that runs in the browser. However, I'm most excited about the ability to write optimized custom arithmetic and buffer manipulations, like, say, fast decimal floating point arithmetic in JavaScript without having to wait for TC39 to get around to it. In this article, I'll show you how to get a couple rudimentary WebAssembly examples running in Node.js, and run a couple trivial benchmarks to show the performance impact.

Collations are another great new feature in MongoDB 3.4. You can think of collations as a way to configure how MongoDB orders and compares strings. In this article, I'll demonstrate some basic uses of collations and show how to use them in Node.js with the MongoDB driver and mongoose.

The most important feature of most server-side frameworks is middleware: the ability to hook your own logic into the framework's logic, like IFTTT for your code. Express, Mongoose, Rails, and Django all rely heavily on middleware. LoopBack and Sequelize have hooks, AngularJS has parsers and interceptors, Hapi has extensions, but these are all just roses by another name. Except Hapi, Hapi by any other name would still have a foul code stench.

The saveErrorIfNotFound option and $where property in mongoose 4.8 gives plugins a powerful new way to modify the behavior of save(). This feature may not seem as exciting as eachAsync() or the major perf improvements in 4.8, but I think it will help the community develop some handy abstractions on top of save(). How do these

The most +1'ed feature request for mongoose in 2016 was extending discriminators to work with embedded documents. Discriminators are mongoose's built-in schema inheritance mechanism. For example, suppose you have a schema defining events:

MongoDB 3.2 supports 3 numeric types: 32 bit integers, 64 bit integers, and 64 bit binary floating points. MongoDB 3.4 introduces a

One of Archetype's core design goals

Static typing is becoming very popular in the JavaScript community. While I'm

Observables have really changed the way I think about JavaScript over

On a sunny Wednesday in September 2006, I showed up for my first day of an

Proxies are a powerful ES2015 feature that let you intercept operations on object properties by defining "traps" (function handlers) for getting/setting a property. For example:

Ramda is quickly becoming an indispensible part of my node projects. Lodash is more accessible and beginner-friendly, but ramda is far more powerful and expressive once you wrap your mind around it. In this article, I'll take a look at the applySpec() function and how it can replace dependency injectors like wagner.

One particularly neat feature of mongoose is the chainable query builder API. This API provides the ability to build up MongoDB queries with helper methods, rather than via a JSON object.

Mongoose 4.5 introduces a new API for populating documents. The new

Mongoose 4.5.0 introduces the ability to handle errors in middleware. This lets

If you haven't heard the React Native hype train yet, you will: it's probably

Mongoose 4.5.0 is just around the corner (current ETA is June 3),

Co is a powerful tool for writing callback-free async code using vanilla ES2015. However, the sheer extent

The practice of asking brainteasers in interviews is a common punching bag

There's a lot of solutions out there for putting private projects in your

The $httpBackend service is definitely one of my top 10 AngularJS features. It makes TDD incredibly easy, especially if you're testing directives as a whole.

Circle CI is quickly becoming my favorite CI tool.

This post originally appeared on StrongLoop provides tools and services for companies developing APIs in Node. Learn more...

Getting data into and out of MongoDB is a pain. Although MongoDB 3.0 and 3.2

This post originally appeared on StrongLoop provides tools and services for companies developing APIs in Node. Learn more...

I must confess, I really don't like most tech books. Except for

2015 was a big year for mongoose. Mongoose 4.0 was released, the first major

In last week's article, you

MongoDB 3.2.0 was released earlier this week. It includes some exciting

This post originally appeared on StrongLoop provides tools and services for companies developing APIs in Node. Learn more...

In the first two articles in this series, you built a

This post originally appeared on StrongLoop provides tools and services for companies developing APIs in Node. Learn more...

This post originally appeared on StrongLoop provides tools and services for companies developing APIs in Node. Learn more...

Strict unit tests are an interesting subject. They're simple, elegant, and do

This post originally appeared on StrongLoop provides tools and services for companies developing APIs in Node. Learn more...

One feature of the current JavaScript language standard, ECMAScript 5,

I've spent a fair amount of time lauding Travis as an excellent go-to CI tool. But, when I wanted to use Travis

Hating "callback hell" is a favorite pastime for many JavaScript bloggers and open source devs.

This blog originally appeared on StrongLoop provides tools and services for companies developing APIs in Node. Learn more...

One of my favorite underused mongoose features is

People have often asked me about my biggest pain points with AngularJS.

This blog originally appeared on StrongLoop provides tools and services for companies developing APIs in Node. Learn more...

Last December, I switched my blog over to a static page generated by a vanilla NodeJS script. So far, its been a dream come true. Thanks to Cesar Devers' design skills, the blog is far more readable than the old standard WordPress template. Also, I can write my posts in Markdown, which has done wonders for my workflow. I also have more direct control over my layout and analytics, so I can use KeenIO to track some basic metrics. Getting to this new blog infrastructure was an adventure. I had brief flings with many static site generators before settling on my current setup. In this article, I'll explain why I decided to skip out on all the established tools and just write my own solution.

Recently, I've been looking into StrongLoop's LoopBack framework. LoopBack generates Express REST APIs by asking you a few simple questions at the command line. LoopBack lets you swap out different storage layers. For each model you define, you can choose to store it in MongoDB, Oracle, MySQL, or Microsoft SQL Server (or even in memory). Say you decide to store your users in MongoDB but your user's gift cards in MySQL (for transactions). Even if you started writing your code with gift cards stored in MongoDB, LoopBack's database abstraction layer makes switching a one-liner. Furthermore, LoopBack has SDKs for generating REST API clients in AngularJS, Android, and iOS. In short, LoopBack is a powerful tool for generating REST APIs that you can extend to scaffold client-side code.

Mongoose 3.9.7 has just been released. While I did say that 3.9.6 would be the

In case you haven't come across Petko Petkov's post on injection attacks against MongoDB and NodeJS yet, its definitely worth a careful read. In this article, he explains a pretty simple exploit that I suspect affects a fair number of applications, including some that I've implemented.

Two weeks ago marked a big milestone: mongoose 3.9.0 was released. Be warned, mongoose's versioning practice is that even numbered branches are stable and odd are unstable. While all our tests check out on 3.9.0, I would recommend sticking to 3.8.x releases in production for now. 3.9.0 was mongoose's first unstable release since October 2013. While the changes in 3.9.0 were relatively minor, they open the door to getting some interesting features into 4.0. Here are some of the high-level features I think should make it in to 4.0:

I have an important announcement to make: over the last couple weeks I've been taking over maintaining mongoose, the popular MongoDB/NodeJS ODM. I have some very big shoes to fill, Aaron Heckmann has done an extraordinary job building mongoose into an indispensable part of the NodeJS ecosystem. As an avid user of mongoose over the last two years, I look forward to continuing mongoose's storied tradition of making dealing with data elegant and fun. However, mongoose isn't perfect, and I'm already looking forward to the next major stable release, 4.0.0. Suggestions are most welcome, but please be patient, I'm still trying to catch up on the backlog of issues and pull requests.

From a performance perspective as well as a developer productivity perspective, MongoDB really shines when you only need to load one document to display a particular page. A traditional hard drive only needs one sequential read to load a single MongoDB document, which limits your performance overhead. In addition, much like how Nas says life is simple because all he needs is one mic, grouping all the data for a single page into one document makes understanding and debugging the page much simpler.

MongoDB shipped the newest stable version of its server, 2.6.0, this week. This new release is massive: there were about 4000 commits between 2.4 and 2.6. Unsurprisingly, the release notes are a pretty dense read and don't quite convey how cool some of these new features are. To remedy that, I'll dedicate a couple posts to putting on my NodeJS web developer hat and exploring interesting use cases for new features in 2.6. The first feature I'll dig in to is text search, or, in layman's terms, Google for your MongoDB documents.

Displaying prices in different currencies is a common internationalization task for web developers. However, this task can be a bit tricky:

In last week's blog post, I showed you how to install all of the basic tools that you need to get up and running with the MEAN Stack. Didn't catch that one and need help getting started with the MEAN Stack? You can find everything you need in Introduction to the MEAN Stack, Part One.

I've received several emails asking for instructions on how to set up a basic MEAN stack app. I'm going to take it one step further and give you guys a two-part post that will walk you through creating your first MEAN stack app- from installing the tools to actually writing the code. In Part One we'll go through the setup and installation process. Next in Part Two we'll walk through the steps for building a very simple to-do list. Part One consists of seven steps, although only the first two are are strictly necessary.

If you're familiar with Ruby on Rails and are using MongoDB to build a NodeJS app, you might miss some slick ActiveRecord features, such as declarative validation. Diving into most of the basic tutorials out there, you'll find that many basic web development tasks are more work than you like. For example, if we borrow the style of, a route that pulls a document by its ID will look something like this:

This post was featured as a guest blog post for MongoDB on April 30th 2013, which can be found here