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Ayobami Ogundiran
Ayobami Ogundiran

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Primitive Data Types in JavaScript.

Welcome to this lesson, in this lesson, we will talk about the primitive data type in JavaScript.

What is a primitive data type?

A primitive data type refers to the smallest unit of data, that is, it has no sub-division. A primitive data type could also be called non-derived data type.

It is any data that is not an object or data that doesn't have its own specific methods.

The primitive data types are basically six in number but if null is included, they are seven in number.

These are the primitive data types or value types.

We have "String", "Number", "Undefined", "Null", "Boolean", "BigInt" and "Symbol". Here, we only talk about four of them because bigint and symbol are a bit advanced for a beginner.

Now, let's talk about String.

String

let name = 'Ayobami';
let school = "Harvard";
let greeting = 'Hello World! I am becoming a developer';
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The values of the above variables are strings because they are texts and they are wrapped with a single or double quote. It is common to use a single quote in JavaScript but both of them are valid.

Let's check the type of the variable school:

console.log(typeof school); // Viola, it shows string in the console. 
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Number

"Number" is another primitive data type in JavaScript. Let's use it.

let age = 20;
let quantity = 7;
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We can use them for arithmetic calculations. That is, we can use number with +, -, /, %, * as in:

let quantity = 7 * 4; // console.log(quantity);
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you should see 28 in the console.

Do you see that?

let price = 20 + 40;
console.log(price);// Yeah! there is 60 in the console.
let remainder = 21 % 4; // console.log(remainder); 
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One is the remainder after dividing 21 by 4.

Now, let's write variable named "quantity" and check its type in the console.

let quantity = 20;
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Don't forget this will throw an error because we cannot re-declare a let variable as we have written earlier.

Okay, let's confirm it.

console.log(typeof quantity); 
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Oops! Do you see that? It throws an error.

Let's just delete one and do console.log(typeof quantity) again.

Gon gon! Its type is number.

And bla bla bla blabla. Let's continue with Boolean.

Boolean

Boolean is used to express true or false value. So, Boolean is used to indicate whether something is true or false as in:

let isYoung = true;// yeah! I am young.
let isMarried = false; Nay! I am single and searching.
let isInteresting = true; My lessons are always on fire (on point);
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let's check the type of isMarried.

console.log(typeof isMarried) // that is boolean.
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It is time for undefined;

Undefined

If you remember, I said in the last lesson that a variable as two parts, name and value, right?

If you only declare its name as in:

let school;
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its value and type will both be undefined.

let's check that by doing

console.log(school);// undefined
console.log(typeof school);// undefined
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Dundrum! You see there is undefined in the console.

Even if you set the value of a variable to undefined, its type and value will both be undefined.

let name = undefined;

console.log(name); // undefined
console.log(typeof name) // undefined
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undefined is logged for both of them in the console.

Finally, let's talk about null.

Null

Null is considered to be a primitive data type. And it means nothing. No data;

Let's use it.

let address = null;
console.log(address)// boom! null.
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let check the type of address.

console.log(typeof address)// object.
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Oooops!

Why object? Shouldn't that be null? That is how it is in JavaScript. Null is a special case of the primitive data type.

Now, you have a good understanding of primitive data type in JavaScript.

Stay connected.

See you in the next lesson?

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