January 2017 – Page 2 – Kev's Development Toolbox

January 14, 2017

Are foldable/flexible phones coming in 2017?

Apple has been criticized in the press from several points of view (for example) that their recent product releases have not been innovative enough, and they’re no longer pushing the boundaries of what’s currently possible. I came across a comment somewhere (I forgot to bookmark it), that the mobile phone industry in general has reached it’s peak of what’s possible, and to continue growth there needs to be a new revolution to innovate beyond the current form factor of the smartphone as we know it today.

I’ve said many times before that each device form factor has unique benefits and limitations according to its size and user interface. For example, a phone that fits in your pocket it a poor replacement for a desktop computer with a large LCD monitor, full size keyboard and mouse, and the reverse holds true too, a desktop computer is hardly a portable computing device.

The recent rumors and articles (in 2015, in 2016 and Lenovo’s concept phone here and here, and more recently: here, here, and here) about new phones from Samsung and LG possibly coming with folding screens starts to blur what’s possible. What if you have a phone that’s small enough and portable to be a phone (as we know it in the current form factor), but it has a screen that unfolds into something larger, say with a 7″ or larger screen that can be used in place of a tablet? That would certainly shake things up, allowing you to carry a device with a large enough screen to sit down and use it at a desk, but still carry it around in your pocket. I’m really curious and hope these come to market soon.

January 10, 2017

Comparing React with ES5 versus React with ES6

Learning React in 2016 seemed like it was stuck halfway transitioning from examples and tutorials using ES5 JavaScript, to the similar but different ES6 JavaScript syntax. If you haven’t done any JavaScript for a while (or at all), it was easy to get confused between the different styles. Even worse, you could easily spend some time reading an article before realizing that it was using ES5 or ES6 syntax and recognizing the differences (or not). As I was learning React, I’m sure I wasn’t the first to paste some ES5 style React syntax into a app using ES6 and get into a complete mess. Once you’ve got to the point of recognizing the differences then it becomes more obvious which is which, and becomes easier to spot an older (and possibly out of date) article with a newer, up to date article.

I like to build example apps to help me understand what’s going on with any new tech or framework, so thought it would be useful to build the same app twice, once using React with ES5 and then rebuild it with React and ES6 as a comparison.

Here’s a rundown of the differences and similarities (I’m sure there’s others too, but these are the ones I’m familiar with).

First up, the entry index.html for each app is mostly the same. The only difference with the ES5 version on the left is that I manually included the webpacked bundle.js, whereas this was done for me from the create-react-app scripts:

Next up, the first index.js to set up the root container component is almost identical. The only difference the JavaScript ES5 using the RequireJS module syntax, versus the ES6 style imports:

Now looking at the AppContainer component. React with ES5 on the left, and ES6 on the right:

Using React with ES5:

uses the React.createClass() api
defines component state using getInitialState()
exports the component as a module using ‘module.exports’

React with ES6:

uses the ES6 class
defines component state using this.state in the constructor()
exports the component as a module using ‘export default’

The render() function is similar in both.

CalculatorComponent – here you’ll notice some more significant differences:

React with ES5:

props are implicit
implicit binding of ‘this’ to functions

React with ES6:

props are passed into the component via the constructor()
explicit binding of ‘this’ to functions in the constructor, using this.functionname.bind(this)

And that’s it! Hope this is a useful reference if you’re looking for a side by side comparison. You can clone my example apps from github here: https://github.com/kevinhooke/ReactJavaScriptComparisons

As I’m still learning as I go, if I’ve misunderstood anything or got anything wrong, please leave a comment and let me know!

January 8, 2017

React: _registerComponent(…): Target container is not a DOM element

Using Webpack with React, it’s critical you import your bundle.js after any DOM elements in your page that you intend to reference. See this issue discussed in this SO question here.

For example:

<body>
<h2>React with ES5</h2>
 <script src="dist/bundle.js"></script>
 <div id="app"></div>
</body>

Importing bundle.js before a DIV element that you reference in your app will result in this error:

Uncaught Error: _registerComponent(...): Target container is not a DOM element.
    at invariant (bundle.js:839)
    at Object._renderNewRootComponent (bundle.js:20668)
    at Object._renderSubtreeIntoContainer (bundle.js:20758)
    at Object.render (bundle.js:20779)

Instead, you need to ensure bundle.js is loaded after the elements you need to reference:

<body>
<h2>React with ES5</h2>
 <div id="app"></div>
 <script src="dist/bundle.js"></script>
</body>

January 7, 2017

New WoSign/StartCom certificates issued after Jan 1st 2017 blocked on Apple products

My first 1 year free SSL certificate with StartSSL is about to expire this month, so time to renew for another year. At this point last year I wasn’t sure what would happen at this point 1 year later, but appears you just apply for another new certificate, and then replace it on the servers where you are using it.

However, once I had requested my new certificate and uploaded it to my OpenShift account, Chrome blocked access to my site with a ‘certificate revoked’ error. I bit of digging turned up this article. Due to a number of security related issues with the Certificate Authority WoSign and later their undisclosed purchase of StartCom/StartSSL, it appears use of certificates from either of these companies are now blocked on all Apple products if issued after Jan 1st 2017, and also on Firefox and Chrome too. More info on Wikipedia here, and Mozilla here and here.