Fold the latest gh-pages blog post back into the next-release branch

_posts/2017-01-31-completing-the-switch-to-es6-classes.md

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+---
+layout: post
+title: Completing the Switch to ES6 Classes
+date: 2017-01-31 15:00:00
+permalink: /blog/2017/01/31/
+---
+
+As I [mentioned](/blog/2016/12/30/) last December, I had started converting PCjs machines to ECMAScript 2015, more
+conveniently known as ES6.  At the time, only one PCjs machine, [PDPjs](/modules/pdp11/), had been converted, which
+left the website in the unfortunate position of having duplicate shared modules: one set for ES5-based machines
+and another set for ES6.
+
+Well, I'm happy to report that today marks the completion of the ES6 conversion, and the return of a single set of
+[shared modules](/modules/shared/lib/).
+
+Admittedly, I was dragging my feet a bit, because the largest and most complex machine emulator, [PCx86](/modules/pcx86/),
+was going to require a fair bit work, not to mention regression testing.  However, after converting three other
+PCjs machines ([PDPjs](/modules/pdp11/), [PC8080](/modules/pc8080/), and [C1Pjs](/modules/c1pjs/)), I had become
+pretty proficient at the conversion, so I was able to bulldoze my way through all the PCx86 files in a few hours,
+and fixing all the Closure Compiler compilation errors only took another hour or so.
+
+It's hard to say whether the conversion was really worth the effort, since I'm still using the Closure Compiler to
+transpile the code back to ES5.  Also, since two of the emulators ([PCx86](/modules/pcx86/) and [PDPjs](/modules/pdp11/))
+can also be launched from the Node command-line, I've adopted Node's *require()* convention for importing the other
+scripts as modules, which makes them difficult to load inside a web browser if you want to test or debug the uncompiled
+code.
+
+To resolve that, I updated the built-in Node web server to "magically" strip out all the Node-specific stuff before
+serving up the individual JavaScript files.  Eventually, I'll change the Node server's page template to use
+`<script type="module" .../>` instead of `<script type="text/javascript" .../>`, but that won't happen until all
+web browsers support module loading AND Node fully supports *import* and *export* instead of *require()* and
+*module.exports*.
+
+I do like the new ES6 class syntax *much* more than the old prototype-based syntax.  We've gone from JavaScript classes
+that were like "lipstick on a pig" to classes that are more like "lipstick on a piglet" -- still a pig, but much cuter.
+
+For years, JavaScript fans have been trying to convince us that "prototypal inheritance" was better and more powerful
+than traditional class-based inheritance models.  As far as I'm concerned, object prototypes were a hack, and no amount
+of after-the-fact rationalizations will convince me that they were actually a thoughtfully designed feature of the
+language.  Not to mention the fact that prototype-based classes are tedious to write and unpleasant to look at.
+
+Obviously, I was not alone, because we now have ES6 classes.
+
+Do I still have gripes?  Sure.  My biggest grumble is that I can't easily define class constants; I have to attach them
+to the class *after* I finish defining the class, and even then, I can't declare them as *const*.  I guess there are
+ways to do it, such as:
+
+	Object.defineProperty(SampleClass, 'ANSWER', {
+		value: 42,
+		writable : false,
+		enumerable : true,
+		configurable : false
+	});
+
+But who in their right mind is going to write all that just to define a single numeric class constant?  I would love to
+be able to add a class constant *inside* a class with a simple: 
+
+	static const ANSWER = 42;
+
+Beyond ES6 classes, there are several other improvements I'd like to make to the PCjs code base, including more
+extensive use of:
+
+- [Default Parameters](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Functions/Default_parameters)
+- *[const](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/const)* and *[let](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/let)*
+- [Computed Properties](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Object_initializer#Computed_property_names)
+
+Those changes will come, but on a more piecemeal basis, as code is visited.
+
+*[@jeffpar](http://twitter.com/jeffpar)*  
+*Jan 31, 2017*