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.
![CSS @supports]()
Feature detection via JavaScript is a client side best practice and for all the right reasons, but unfortunately that same functionality hasn't been available within CSS. What we end up doing is repeating the same properties multiple times with each browser prefix. Yuck. Another thing we...
![5 Awesome New Mozilla Technologies You’ve Never Heard Of]()
My trip to Mozilla Summit 2013 was incredible. I've spent so much time focusing on my project that I had lost sight of all of the great work Mozillians were putting out. MozSummit provided the perfect reminder of how brilliant my colleagues are and how much...
![Pure CSS Slide Up and Slide Down]()
If I can avoid using JavaScript for element animations, I'm incredibly happy and driven to do so. They're more efficient, don't require a JavaScript framework to manage steps, and they're more elegant. One effect that is difficult to nail down with pure CSS is sliding up...
![Shake Things Up Using jQuery UI’s Shake Effect]()
Yesterday I created a tutorial showing you how you can shake an element using Fx.Shake, a MooTools component written by Aaron Newton. It turns out that jQuery UI also has a shake effect which can draw attention to an element.
The XHTML
Exactly the same as...
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:
A lot of people think you have to do something like:
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.