JavaScript’s prototypal inheritance

In this final part of our series on JavaScript prototypes, we’re going to discuss using them to implement inheritance as it’s typically thought of in classical object-oriented design. Having said that, I once again suggest that you try to put aside what you may already know about how objects and inheritance work in other languages and treat the way JavaScript works as its OwnThing.

So, let’s get on with it.

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The JavaScript prototype chain

So far we’ve learned what the relationship is between an object and its constructor’s prototype and what happens when we change properties set on the prototype. In particular, we learned that if you try to access a property of on object, the JavaScript engine will first look in the object itself for the property, and it if doesn’t find it there it looks in its __proto__ property, which is also the constructor’s prototype.

This leads to a good question: What happens if the property isn’t in the constructor’s prototype either? One possible answer is that the JavaScript engine gives up and says the property is undefined. But that’s not what happens.

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Designing out designers?

I’m teaching myself React, the JavaScript library du jour that’s meant “for building user interfaces.” Interestingly, it doesn’t use a templating language. Instead it offers JSX: an extension of the JavaScript language that lets you write JS code that looks very much like HTML and that can be rendered into HTML. On the surface this seems like a cool idea, but the apparent simplicity starts to break down when you want to do anything other than straight-line HTML.

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JavaScript prototypes

This is the first in a series of posts intended as a gentle guide through the realm of JavaScript prototypes. If you’re coming here from a class-based language like Java, PHP, C#, or C++ I suggest you put aside everything you know about how objects and inheritance work in those languages. Try to treat the way JavaScript works as its OwnThing.

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JavaScript and ‘this’

Keeping your head square about JavaScript’s this variable can be a little challenging. A wonderfully concise summary on the issue is found in chuckj’s answer to a StackOverflow question (modified here to account for differences between ECMAScript 5’s strict and non-strict modes):

this can be thought of as an additional parameter to the function that is bound at the call site. If the function is not called as a method then the global object (non-strict mode) or undefined (strict mode) is passed as this.”

Let’s see what this means (pun intended?) for various scenarios.

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What is a single-ended amplifier?

Single-ended amplifiers, whether made with triodes (as in the single-ended triode, or SET, amplifier), pentodes, or solid state devices, entered the high-end consumer audio consciousness a couple decades ago, and they continue to have a particular pull for a certain camp of audiophiles. This may lead the rest of us to wonder whether these folks are onto something that we should pay attention to. However, there seems to be some confusion regarding what exactly single-ended amplifier are. So I thought I’d try to clear things up a little.

So, what exactly is a single-ended amplifier?

It might be easier if we first cover what isn’t a single-ended amplifier.

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Displays for classic Arduinos

Arduino driving TFT display

You often hear that to work with graphic displays on the Arduino platform you need to use a Mega or other high-performance board. I got curious about how much you can actually get done on an a measly Uno and similar boards based on the classic ATmega328P. You can find the ongoing results on my wiki.

The story so far: 128×64 and smaller monochrome displays are usable. The smallest TFT displays much less so.

AVA preamp chassis

AVA “SLR” remote controlled preamplifier chassis

A recent chassis redesign project I undertook for Audio by Van Alstine is now in production.

This project pushed “constraints as creative resource” to the limit. The client specified that the design language and elements from the product’s predecessor be maintained—down to the knobs, faceplate treatments, and typography.

The project brief revolved around electronic and industrial design work to bring the client’s preamplifer platform up to functional parity with current market offerings within a framework that fits with the client’s existing manufacturing capabilities. The result is a platform that is significantly more capable than what it replaces yet easier for the client to manufacture. It is also amenable to comprehensive appearance changes if and when the client deems the timing is right.

So while it might not seem there’s much innovation on the outside, there is a lot of innovation for the client on the inside.