December 2014
Intermediate to advanced
346 pages
6h 14m
English
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Referencing deep properties safely using $parse
When dealing with object access, a seasoned JavaScript developer will be quite familiar with this error message:
TypeError: Cannot read property '...' of undefined
This, of course, is the result of attempting to access a property on an object that does not exist in the current lexical scope. It is often the case that the developer is aware of the possibility that the referenced object can be undefined, but it would be preferred that a failed property access returns undefined instead of throwing an error.
How to do it…
The typical use case is an asynchronous method that references a piece of data that isn't necessarily initialized before use.
Suppose that the user object in this example is populated with ...
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.