Access JavaScript Object Variable Properties
Not all JavaScript objects are as easy as MyObject.property. Sometimes you may want to access a property whose key is stored in a variable. Luckily accessing these properties is very easy.
Javascript Object Property Accessing Example
/* setting */
var myObject = {
left : 30,
top: 20
};
/* basic access */
var left = myObject.left; //OR
var left = myObject['left'];
/* accessing it or variables */
var mode = 'vertical';
var value = myObject[mode == 'horizontal' ? 'left' : 'top'];
You may use array-style syntax to access an object's properties. The string within brackets returns the properties.
![Page Visibility API]()
One event that's always been lacking within the document is a signal for when the user is looking at a given tab, or another tab. When does the user switch off our site to look at something else? When do they come back?
![From Webcam to Animated GIF: the Secret Behind chat.meatspac.es!]()
My team mate Edna Piranha is not only an awesome hacker; she's also a fantastic philosopher! Communication and online interactions is a subject that has kept her mind busy for a long time, and it has also resulted in a bunch of interesting experimental projects...
![CSS calc]()
CSS is a complete conundrum; we all appreciate CSS because of its simplicity but always yearn for the language to do just a bit more. CSS has evolved to accommodate placeholders, animations, and even click events. One problem we always thought...
![Sexy Opacity Animation with MooTools or jQuery]()
A big part of the sexiness that is Apple software is Apple's use of opacity. Like seemingly every other Apple user interface technique, it needs to be ported to the web (</fanboy>). I've put together an example of a sexy opacity animation technique...
I’m a big fan of myObject[key] as its close to the PHP array syntax. Just personal preference really and it gives great flexibility and easy to test for.
@Colin – I just love how object property keys and array indexes are treated as equal in Javascript. The closest to this coolness that PHP comes is in pseudo-property keys ($obj->$var_key)
never knew this method, very useful.
@Chris – PHP’s ArrayObject class allows you to access properties using array syntax.
@keith – huh…never knew that. Thanks! :D
It’s a good thing to point out that you can almost always avoid eval() by use of myObject[‘key’] reference. for example:
var myObject = {}; $H({ 'a': 1, 'b': 2, 'c': 3 }).each(function(v, k) { myObject[k] = v; });A lot of people think you have to do something like:
var myObject = {}; $H({ 'a': 1, 'b': 2, 'c': 3 }).each(function(v, k) { eval('myObject.' + k + ' = ' + v); });Avoid eval! Eval is evil.
@Timothy: While it is preferable to avoid eval in code that need not be written in that form, as you show, I would like to contest that eval is far from evil.
It’s a basic language construct upon which the entire functional programming paradigm can be built in languages that do not support it natively. Sometimes a problem is better expressed in said paradigm, but the language prevents you from properly exploiting it’s capabilities. This is one of the many ways eval *can* be used for the better of your programming speed, debug-ability and general style of programming.
So please, next time you wish to share your opinion on eval, try to think of the grand picture this language construct fits in, and don’t spread lies about otherwise finely crafted implementations thereof.
Thank you! I was stumped but this got me back on track.
Thank you soooo much, didn’t know this was possible. Spent countless hours trying to refactor my object to make calls easier, wish someone told me about this earlier lol.