Immediately Executing Functions
JavaScript is full of nifty little tricks to accomplish tasks with less code. One of those tricks is immediately executing functions. We oftentimes see this pattern for executing anonymous functions to limit variable scope:
(function() {
console.log('executed!');
// Do processing here
})();
What many developers don't know is that this code can be shorted by using a ! before the anonymous function:
!function() {
console.log('executed!');
// Do processing here
}()
The function above executes immediately, just as the first snippet did. One caveat: the immediately executing function always returns false. If you desire the result of the anonymous function, you wont want to use this second pattern.
Ben Alman has created an excellent, detailed writeup on the subject and if you want to learn more, be sure to visit his post!
![7 Essential JavaScript Functions]()
I remember the early days of JavaScript where you needed a simple function for just about everything because the browser vendors implemented features differently, and not just edge features, basic features, like addEventListener and attachEvent. Times have changed but there are still a few functions each developer should...
![Animated 3D Flipping Menu with CSS]()
CSS animations aren't just for basic fades or sliding elements anymore -- CSS animations are capable of much more. I've showed you how you can create an exploding logo (applied with JavaScript, but all animation is CSS), an animated Photo Stack, a sweet...
![MooTools History Plugin]()
One of the reasons I love AJAX technology so much is because it allows us to avoid unnecessary page loads. Why download the header, footer, and other static data multiple times if that specific data never changes? It's a waste of time, processing, and bandwidth. Unfortunately...
![9 More Mind-Blowing WebGL Demos]()
With Firefox OS, asm.js, and the push for browser performance improvements, canvas and WebGL technologies are opening a world of possibilities. I featured 9 Mind-Blowing Canvas Demos and then took it up a level with 9 Mind-Blowing WebGL Demos, but I want to outdo...
Because not quite enough people pulled out their hair on encountering the function(){…}() syntax.
The first is not exactly valid. The right call has the call-parentheses inside the container parentheses.
(function() { ... code ... }())I think the ! is works with call-parentheses too. So it’s not shorter.
> !function(){console.log('asd')} false > !function(){console.log('asd')}() asd true > function(){console.log('asd')}() asd undefined > (function(){console.log('asd')}()) asd undefined >I think such oddities should be removed from the language.
What would ever be the argument for doing this? A Obfuscated Javascript Code Contest?
Why even use such a function? I don’t get it. If you want code to execute immediatly, just write it outside a ‘function’. What’s the point of an anonymous function you can’t call later on for reusability? Or am I missing something?
Encapsulation of vars…