JavaScript

When Does a Project Need React?

You know when a project needs HTML and CSS, because it's all of them. When you reach for JavaScript is fairly clear: when you need interactivity or some functionality that only JavaScript can provide. It used to be fairly clear when we reached for libraries. We reached for jQuery to help us simplify working with the DOM, Ajax, and handle cross-browser issues with JavaScript. We reached for underscore to give us helper functions that the JavaScript alone didn't have.

As the need for these libraries fades, and we see a massive rise in new frameworks, I'd argue it's not as clear when to reach for them. At what point do we need React?

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ES6 modules support lands in browsers: is it time to rethink bundling?

Modules, as in, this kind of syntax right in JavaScript:

import { myCounter, someOtherThing } from 'utilities';

Which we'd normally use Webpack to bundle, but now is supported in Safari Technology Preview, Firefox Nightly (flag), and Edge.

It's designed to support progressive enhancement, as you can safely link to a bundled version and a non-bundled version without having browsers download both.

Stefan Judis shows:

<!-- in case ES6 modules are supported -->
<script src="app/index.js" type="module"></script>
<!-- in case ES6 modules aren't supported -->
<script src="dist/bundle.js" defer nomodule></script>

Not bundling means simpler build processes, which is great, but forgoing all the other cool stuff a tool like Webpack can do, like "tree shaking". Also, all those imports are individual HTTP requests, which may not be as big of a deal in HTTP/2, but still isn't great:

Khan Academy discovered the same thing a while ago when experimenting with HTTP/2. The idea of shipping smaller files is great to guarantee perfect cache hit ratios, but at the end, it's always a tradeoff and it's depending on several factors. For a large code base splitting the code into several chunks (a vendor and an app bundle) makes sense, but shipping thousands of tiny files that can't be compressed properly is not the right approach.

Preprocessing build steps are likely here to stay. Native tech can learn from them, but we might as well leverage what both are good at.

Debugging Tips and Tricks

Writing code is only one small piece of being a developer. In order to be efficient and capable at our jobs, we must also excel at debugging. When I dedicate some time to learning new debugging skills, I often find I can move much quicker, and add more value to the teams I work on. I have a few tips and tricks I rely on pretty heavily and found that I give the same advice again and again during workshops, so here's a compilation of some of them, as well as some from the community. We'll start with some core tenets and then drill down to more specific examples.

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HTML APIs: What They Are And How To Design A Good One

Lea Verou writes about the design of HTML APIs and how we might write better documentation for web designers. An HTML API is term for a JavaScript library that is configured and controlled through HTML rather than through JavaScript. For example <div data-open-modal="#modal"></div> might tell a library that this element is in charge of opening a modal. There is no configuration or initting other than loading the library itself.

My favorite part of this piece is where Lea confronts what might generally be seen as a simple plug-n-play JavaScript library:

Even this tiny snippet of code requires people to understand object literals, arrays, variables, strings, how to get a reference to a DOM element, events, when the DOM is ready and much more. Things that seem trivial to programmers can be an uphill battle to HTML authors with no JavaScript knowledge

By giving folks an HTML API we can avoid potential headache.

...remember that many of these people do not speak any programming language, not just JavaScript. Do not talk about models, views, controllers or other software engineering concepts in text that you expect them to read and understand. All you will achieve is confusing them and turning them away.

Lea's made a collection of libraries that have HTML APIs.

JavaScript Start-Up Performance

Addy Osmani:

Smaller JavaScript bundles generally do result in a faster load time (regardless of our browser, device & network connection) but 200KB of our JS !== 200KB of someone else's and can have wildly different parse and compile numbers.

Using file size as a metric isn't an awful crime, because it does matter, but it's only part of the JavaScript performance story.

I also found the overview of the discussion of bytecode interesting. Browsers download JavaScript, parse it, turn it into an abstract syntax tree, then turn that into bytecode. What if we could do that during our build steps and ship bytecode?

My opinion is shipping bytecode can increase your load-time (it's larger) and you would likely need to sign the code and process it for security. V8's position is, for now, we think exploring avoiding reparsing internally will help see a decent enough boost that precompilation may not offer too much more, but are always open to discussing ideas that can lead to faster startup times.

Intro to Vue.js: Animations

This is the fifth part in a five-part series about the JavaScript framework, Vue.js. In this last part of the series, we'll cover Animations (if you know me at all, you probably knew this was coming). This is not intended to be a complete guide, but rather an overview of the basics to get you up and running so you can get to know Vue.js and understand what the framework has to offer.

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Intro to Vue.js: Vuex

This is the fourth part in a five-part series about the JavaScript framework, Vue.js. In this part, we'll cover Vuex for state management. This is not intended to be a complete guide, but rather an overview of the basics to get you up and running so you can get to know Vue.js and understand what the framework has to offer.

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