December 2012
Beginner
164 pages
3h 15m
English
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Chapter 6. The this Keyword
Conceptual Overview of this and How It Refers to Objects
When a function is created, a keyword called this is created (behind the scenes), which links
to the object in which the function operates. Said another way, this is available to the scope of its function,
yet is a reference to the object of which that function is a
property/method.
Let’s take a look at the cody object from Chapter 1 again:
<!DOCTYPE html><html lang="en"><body><script>
var cody = {
living : true,
age : 23,
gender : 'male',
getGender : function() {return cody.gender;}
};
console.log(cody.getGender()); // logs 'male'
</script></body></html>Notice how inside of the getGender function, we are accessing the
gender property using dot notation
(e.g., cody.gender) on the
cody object itself. This can be rewritten using
this to access the
cody object because this points to the cody
object.
<!DOCTYPE html><html lang="en"><body><script>
var cody = {
living: true,
age: 23,
gender: 'male',
getGender: function() {return this.gender;}
};
console.log(cody.getGender()); // logs 'male'
</script></body></html>The this used in this.gender simply refers to the
cody object on which the function is operating.
The topic of this can be
confusing, but it does not have to be. Just remember that, in general,
this is used inside of functions to
refer to the object the function is contained within, as opposed to the
function itself [exceptions include using the new keyword or call() and apply()
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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.