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!
![Detect DOM Node Insertions with JavaScript and CSS Animations]()
I work with an awesome cast of developers at Mozilla, and one of them in Daniel Buchner. Daniel's shared with me an awesome strategy for detecting when nodes have been injected into a parent node without using the deprecated DOM Events API.
![An Interview with Eric Meyer]()
Your early CSS books were instrumental in pushing my love for front end technologies. What was it about CSS that you fell in love with and drove you to write about it?
At first blush, it was the simplicity of it as compared to the table-and-spacer...
![Unicode CSS Classes]()
CSS class name structure and consistency is really important; some developers camelcase classnames, others use dashes, and others use underscores. One thing I've learned when toying around by HTML and CSS class names is that you can actually use unicode symbols and icons as classnames.
![Growl-Style Notifications Using MooTools Roar]()
When I think of premier MooTools plugin developers, Harald "digitarald" Kirschner is usually one of the first people that come to mind. Harald has built some of MooTools' most popular plugins, including AutoCompleter, FancyUpload, and History Manager. My favorite plugin created...
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…