WEBVTT

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In this video you're going to learn read only variables in E6 or what we call constants so a constant

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is a variable thus can most be reassigned a new value.

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Once you define it so as to create constants you use the keyword constants and then you choose a name

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for your variable.

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Usually you find these variables in uppercase.

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Now if you just declare the variable without initializing it you're gonna get an error.

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So you really need to initialize its streets after declaration.

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So let's set this variable to up.

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So if you log

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make you're gonna get apple now.

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If you try to assign a new value to make like something then you're gonna get an error because as we

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said these variables are constants so they cannot be reassigned.

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New values now constants just like lets variables they are block skipped.

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So if you create separate blocks and you read declare your constants

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in these scopes then this is not going to cause any error because they are block skipped.

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Now a quick challenge for you let's set a constant to a value which is gonna be an object so let's call

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it what language

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and let's say about.

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He's gonna have a couple of properties.

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So the name javascript and a version is five.

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So now we know that this is a constant.

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So you cannot assign a new value to it.

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But what if you assign a new value to one of its properties so let's change the Virgin to 6 for example.

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Do you think this is gonna cause an error.

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Well let's find out.

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So this is working just fine.

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You will get an error.

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Only if you do language equals something.

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So you're you're actually reassigning or assigning a new value to the constants itself instead of the

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properties of the object.

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All right.

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So now the good practice in E6 is to use constants all the time unless you are looping or need reassigned.

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So in my case you use let me it's okay to use var if you wish.

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It's a good proxy to use constants or variables that don't change.