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I've learned javascript at school but since I'm working with it and study about it every day, I've found very particular aspect of javascript that I didn't know about. Which at first, was very hard to understand for me and finally, I found it very usefull and easy to implement. And in the final, it gives to my code some kind of "beauty".

An example I've once seen:

function getter( input )
    result = {
        foo1 : 'bar1',
        foo2 : 'bar2',
        foo3 : 'bar3'
    }[input] || input || "default";

    return result;

Do you guys have other examples of particular use you make of Javascript ?

Thank you

PS: I use the term particular use because it might be unusual for any Javascript beginner. I believe this question is most likely to belong to the community wiki.

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migrated from Feb 3 '11 at 16:59

This question came from our site for professional and enthusiast programmers.

Since this doesn't have an objective answer, it should probably be a Community Wiki. –  user12157 Feb 2 '11 at 15:20
@patrick dw, I totally agree but I can't convert/create a community wiki post. –  Cybrix Feb 2 '11 at 15:22
I see. I didn't realize that more rep was needed to make a CW. There's no CW checkbox under the question's edit area? EDIT: Just looked at meta, and sure enough, only moderators can do it now. –  user12157 Feb 2 '11 at 15:25
@patrick dw, for some reason only 10 reputations is required to create wiki post. But the checkbox wasn't there and in fact, I've not seen it for a while. (When I created my account before I remember that checkbox). –  Cybrix Feb 2 '11 at 15:31
@Cybrix: Yeah, there are some posts on meta indicating that now only moderators can do it. –  user12157 Feb 2 '11 at 15:33

3 Answers 3


The following example applies an “negative” class on every input element who’s numeric value is below 0.

(function (elements) {
    for (var i = 0; i < elements.length; i++) {
        if ((elements[i].value * 1) < 0) {
            elements[i].className = 'negative';

In an effort to protect the global object, all JavaScript applications should be written within a self-invoking function. Although, this is a very basic concept, I found this real odd, unusual, cool and exciting at the same time.

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Also one of the idiomatic ways of creating event handlers in a loop (to avoid the handlers closing over the same binding). –  Jesse Millikan Feb 3 '11 at 17:24


jQuery makes such extensive use of closures and wrapping objects that it pretty much turns JavaScript into a completely different language.


$('ul.level-2').children().css('background-color', 'red');


jQuery is interesting in that often it's completely ambiguous whether you have a single element or a list of elements, and as a result most (all?) of the same functions can be run in either case.

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actually in jQuery you always have a list, it just may be a list of 1 element. –  Zachary K Feb 16 '11 at 13:46

I tend to do a lot of list operations and recursion. Almost treating javascript as if it was lisp.

somthing like this

   function getNegative (elements){ 
      return elements.filter(function (el){  return el< 0; });

very clean and easy to understand

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Yes indeed it's very clean. –  Cybrix Feb 16 '11 at 14:09
actually I will often stack array ops, put 3-5 of them in a row, each one is generally a function of 1-3 lines of code. –  Zachary K Feb 16 '11 at 14:23

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