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Welcome back to Learn to Code and JavaScript.

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Next, we're going to talk about primitive data types.

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So what are the primitive data types?

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So one is called undefined and we'll see an example that it just means something has no definition.

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Bullion is a data type that can be true or false.

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Numbers can be whole numbers or decimal numbers.

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And they have a certain range.

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Strings are set of zero more characters like Hello, World is a strange.

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Big event is an arbitrary precision, no, you using things like cryptography and things like that where

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you need really, really long numbers.

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And several produces a unique value of these we're only going to be focusing on undefined billion number

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and string.

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So literal data versus variables, a literal value like the number two, can only be used once.

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So you put it in the program, you say Castletown log too, and that too, you can repeat it, but it's

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a different version of that to so undefined has a value of undefined boolean.

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A literal value could look like true numbers.

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It could look at one zero twenty two point five six seven.

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And if you haven't seen this before, it looks so different to point to five, six, seven E one.

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The E is an exponential notation or scientific notation, which means times 10 to the first.

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So that number and twenty two point five, six, seven are equivalent.

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Strength, we've seen some of these before, however, with Dovecote, good Bárbara with single quotes.

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Twelve point twenty two in quotes is a string, not a number, true in quotes is a string, not a no.

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A variable stores value could be used again.

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And for primitive, dated variables are immutable.

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And what this means is that if you cannot really be changed, you just get a new copy of it.

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Variables are stored in computer memory is one or more bytes and a bite has eight bits of zeros or ones.

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So, for example, a number is two bites, I'm sorry.

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Number is, I think eight bites and there eight bites of zeros and ones, a character and a string of

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two bites.

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That has a representation of that character.

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Variable scope variables are defined in a scope, and we talk about the scope of a function in the previous

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structure, which is the space between curly braces.

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We want to avoid is global scope because then you can have like side effects and we'll take a look at

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that.

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Some keywords, VA, which is an old way to declare variables and JavaScript, but it declares it in

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global scope, don't use it.

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You'll see it being used, but you should not use it because it's been replaced by LET, and that lets

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you define a new variable or contract which allows you to declare a variable that cannot be reassigned,

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a new value.

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JavaScript uses dynamic variable definition so a variable can have different types, so you could say

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let X equals three.

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That's the way to define it, variable X, that's the number that has the value of three.

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But you can turn right around and say X equals hello.

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As a stray.

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So now X is a string, not a no.

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And then you can say X equals true.

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So some information about scope and you've also seen this word at the top, secret mode you stripped.

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And look at a definition of that, but what it does is prevents use of undeclared variables.

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And then scope, as I mentioned, is the boundaries of the left, curly brace and right curly brace

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for variables are known and defined.

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So we'll look at a couple of examples of that.