Shaving Bytes with JavaScript Booleans
Developers are always search for ultimate way to create something with the least amount of code. This, of course, is one of the reasons we use minifiers: to serve code as small as possible. Of course this practice has numerous benefits, like faster download time, less storage consumption, etc. One way that minifiers are able to shave bytes off of JavaScript code is changing the way booleans are used.
true === !0 // Save 2 chars
false === !1 // Save 3 chars
A few bytes of every true and false go away with the ! evaluation. If you set one-letter variables names to those values, you may end up saving more. Keep in mind I'm not telling you to do this in your source code -- minifiers like Uglify JS will do this for you. Just something neat to know about though!
![Facebook Open Graph META Tags]()
It's no secret that Facebook has become a major traffic driver for all types of websites. Nowadays even large corporations steer consumers toward their Facebook pages instead of the corporate websites directly. And of course there are Facebook "Like" and "Recommend" widgets on every website. One...
![5 HTML5 APIs You Didn’t Know Existed]()
When you say or read "HTML5", you half expect exotic dancers and unicorns to walk into the room to the tune of "I'm Sexy and I Know It." Can you blame us though? We watched the fundamental APIs stagnate for so long that a basic feature...
![Flashy FAQs Using MooTools Sliders]()
I often qualify a great website by one that pay attention to detail and makes all of the "little things" seem as though much time was spent on them. Let's face it -- FAQs are as boring as they come. That is, until you...
![Making the Firefox Logo from HTML]()
When each new t-shirt means staving off laundry for yet another day, swag quickly becomes the most coveted perk at any tech company. Mozilla WebDev had pretty much everything going for it: brilliant people, interesting problems, awesome office. Everything except a t-shirt.
That had to change.
The basic...
Cool :-)
Glad you aren’t advocating coding like this directly. Can’t beat true/false for readability.
Coercions like
NumbertoBooleandoesn’t affect performance?Maybe too simple of a test: http://jsperf.com/bool-num-test
Looks like using
!0and!1may be faster (in Chrome 35) but only marginally.Even if that’s true, and it’s not due to some statistical error, the gain is so small it’s not really worth it.
Those are noops anyway. I would be surprised if the JS engine just optimise them away at compile time.
didn’t just*
Still prefer true/false for readability. As you said, it is better to let the Minifier to do this for us. It is better to keep the true/false in our code.
I expect the gain to be lost as soon as the file gets gzipped. I am wrong?
You should also remember the bitwise operations like
!~number, that returns true only for -1