We've all been there. You've received a giant JSON response from some API, you parse it into an object, and you want to reach in several levels deep to retrieve a property if the path exists.
After all, you may not know the exact structure of the object - indeed, its structure may be unpredictable.
Let's say we have this object:
What if we want to retrieve the etc property, but we're not sure if the path to it exists? Previously, we'd have had to do something laborious like this:
If the path doesn't exist - say, if our object was completely empty - and we simply do
...we'll get an error saying
Uncaught TypeError: obj.foo is undefined
Makes sense; we're trying to get
foo is undefined, since our object is empty. We could use an object XPath library such as my very own J-Path, but that would probably be overkill until you were doing a lot of this.
These days there's a much cleaner way of dealing with this. ECMAScript 11, which landed last year, brought with it something called the optional chaining operator, which looks like
Now we can simply do:
If the path exists, we'll get the value. If it doesn't, we'll get undefined - but no show-stopping errors. Pretty cool, right!?
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