Object.keys
I adore JavaScript objects. Love them. You're probably asking "well, why don't you marry them?" Trust me: if I could, I would. Arrays are nice and all but object keys provide another level of structure and information that is invaluable. For example, it's much faster search an object for a key than it is to search an array for value presence.
The way we've always iterated on an Object
instance was always a for
loops with a hasOwnProperty
check which was ugly; Object.keys
(not Object.prototype.keys
) provides an array of Object properties!
var person = {
firstName: 'David',
lastName: 'Walsh',
// ...
};
Object.keys(person).forEach(function(trait) {
console.log('Person ', trait,': ', person[trait]);
});
If you work with JSON or simply raw JavaScript objects, and you haven't been using Object.keys
, now is the time to ditch the old method for this elegant solution!
![9 Mind-Blowing WebGL Demos]()
As much as developers now loathe Flash, we're still playing a bit of catch up to natively duplicate the animation capabilities that Adobe's old technology provided us. Of course we have canvas, an awesome technology, one which I highlighted 9 mind-blowing demos. Another technology available...
![Vibration API]()
Many of the new APIs provided to us by browser vendors are more targeted toward the mobile user than the desktop user. One of those simple APIs the Vibration API. The Vibration API allows developers to direct the device, using JavaScript, to vibrate in...
![Printing MooTools Accordion Items]()
Sometimes we're presented with unforeseen problems when it comes to our JavaScript effects. In this case, I'm talking about printing jQuery and MooTools accordions. Each "closed" accordion content element has its height set to 0 which means it will be hidden when the...
![Jack Rugile’s Favorite CodePen Demos]()
CodePen is an amazing source of inspiration for code and design. I am blown away every day by the demos users create. As you'll see below, I have an affinity toward things that move. It was difficult to narrow down my favorites, but here they are!
Why don’t you use this:
@Franz,
for..in iterating over NON own properties.
Not very well supported http://caniuse.com/#feat=let
Obligatory https://babeljs.io/
Also would iterate over prototype properties.
The
for each...in
statement is deprecated as the part of ECMA-357 (E4X) standard. E4X support has been removed, butfor each...in
will not be disabled and removed because of backward compatibility considerations. Consider usingfor...of
instead. (Please refer to bug 791343.)Also: Use
const
, not let. The loop creates a new context in each iteration, the loop variable therefore is constant unless your loop-code changes it.