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.
![Regular Expressions for the Rest of Us]()
Sooner or later you'll run across a regular expression. With their cryptic syntax, confusing documentation and massive learning curve, most developers settle for copying and pasting them from StackOverflow and hoping they work. But what if you could decode regular expressions and harness their power? In...
![6 Things You Didn’t Know About Firefox OS]()
Firefox OS is all over the tech news and for good reason: Mozilla's finally given web developers the platform that they need to create apps the way they've been creating them for years -- with CSS, HTML, and JavaScript. Firefox OS has been rapidly improving...
![Introducing MooTools ScrollSide]()
This post is a proof of concept post -- the functionality is yet to be perfected.
Picture this: you've found yourself on a website that uses horizontal scrolling instead of vertical scrolling. It's an artistic site so you accept that the site scrolls left to right.
![TextboxList for MooTools and jQuery by Guillermo Rauch]()
I'll be honest with you: I still haven't figured out if I like my MooTools teammate Guillermo Rauch. He's got a lot stacked up against him. He's from Argentina so I get IM'ed about 10 times a day about how great Lionel...
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.