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Static Methods
3:05What are static methods and how should they be used? Watch this video to find out!
When declaring a method on a class we
have two options instance or static.
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In this video I'll show you what a static
method is and how they can be useful.
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And if you'd like to follow along
open the workspace for this video.
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A static method is one that exist
on the class decoration and
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is not accessible through an instance.
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You can only call the function
by referencing it's class.
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In the file static.js I have
a bird class with a static method
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called change color and
by default the color is set to red.
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Now the interpreter knows
this is a static function
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because the line starts
with the static keyword.
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So let's see how this works.
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First, I'll create a new bird,
I'll call it redBird,
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since that's the default color.
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Then I'll log the initial
value of redBird's
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color by saying console.log redbird.color.
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Next, I'll call change color on redBird,
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by typing redBird.changecolor, and
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I'll set the color to blue.
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And finally, I'll log the current
value of redBird's color,
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with console.log redBird.color.
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So, let's see what happens.
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Over in the console,
I'll run node static.js and
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it looks like I get an error.
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It says red bird that change color
is not a function well since
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change color is a static method I can't
access it through my redBird instance.
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Now we can do a couple of things to fix
this the quickest solution is to call
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change color with our
instance as the context.
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So over in the changed
color call we can say
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Bird.changeColor.call then pass redBird,
then blue.
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So here the static method takes
the instance of redBird and
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applies the color change.
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So over in the console we can see that
the color changes from red to blue.
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The other thing we can do is
rewrite the static method
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to take an instance as a parameter.
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So over in the static method
we'll pass the parameter bird and
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then instead of this.color
will change it to bird.color.
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By passing the instance to
the method we avoid confusion
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of how the method is to be used.
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So now I can call change color
without using the call method, right?
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So over in the consul if I
run node static.js, perfect.
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Great job following along.
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In the next video we'll look at using
getter and setter methods in a class.
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