- not understanding truthy / falsy values
- not testing default values correctly
- using wrong comparison operators (just use === or !==)
- not using for .. in properly (because of prototype bleed-through)
- misunderstanding scope (with great discussion of variable hoisting)
- not using closures properly
- putting things in the global scope incorrectly
ECMAScript 5: The New Parts
The most notable new parts:
- Object.create() is now part of the spec
- native JSON processing
- array methods (filter, forEach, indexOf, lastIndexOf, reduce, map, every, some)
- new Date methods (now, toISOString)
- Attributes (things like writable, enumerable, configurable)
- getters and setters are available for objects
- Object extensibility controls (seal, freeze, preventExtensions)
- Object.keys which returns an array of own properties (goodbye hasOwnProperty check)
- ‘use strict’ option
You can do really complex things quite easily with this library. For example, you can process a stream of events by applying filtering to it with a simple, fluent interface.
By the way, this presentation has one of the coolest uses of PowerPoint I’ve ever seen: Visual Studio “debugger” mode. Well done!
The magical part is that the updates are automatic. As in, Knockout automatically tracks dependencies between display elements and properties in your model. It can also do many more awesome things, like iterate through a collection of items associated to an object declaratively (without writing code).
Making Better Web Apps For Today’s Browsers
In his talk, James Mickens from Microsoft Research presented two really interesting frameworks called Silo and Footprints (formerly Mugshot).
- next version of ECMAscript (after 5) will most likely address modularity
- they tried, but failed to kill eval in version 5
- they actually considered altering the syntax to be more CoffeeScript like, but decided against it
Fonts, Form and Function: A Primer on Digital Typography
Not directly related to web development, but a great (and beautifully put together) presentation from Robby Ingebretsen of Pixel Lab on typography basics.
* You can find all of the videos from the event here.
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