JavaScript happens to be one of the most popular programming language in 2021. One of the reasons is because it's the only programming language used on the front-end web development. If you are looking forward to be a web dev, then JavaScript is very important to understand. One of the core concepts is JavaScript is Data Types
. In this blog post we will cover data types in depth.
JavaScript is Dynamically typed
🔹 A value in JavaScript is of a certain type.
🔹 Types in JavaScript are not bound to variables.
🔹 This means that you don't specify the types when declaring a variable.
🔹 JavaScript is therefore said to be a Dynamically typed programming language.
🔹 You will also find some blog posts calling it loosely typed
. It means the same thing.
- See below ⬇
JavaScript has 8 data types.
The 7 primitive data types:
🔹 Boolean
🔹 null
🔹 undefined
🔹 Number
🔹 BigInt
🔹 String
🔹 Symbol
The non-primitive data type:
🔹 Object
- Note that arrays and functions are objects.
- Functions are special objects with a function value.
- See below ⬇
Difference between primitive types and non-primitive types
🔹 Primitives have immutable values (cannot be changed)
🔹 non-primitive have mutable values (can be changed)
- Don't confuse changing a value with changing a variable
- Variables are not values
- See below ⬇
🔹 Primitives are compared by value. The same values are strictly equal. They exist at the same memory location.
🔹 non-primitive are not compared by value. Two objects with the same properties and values are not equal. They are created at different memory locations.
- See below ⬇
Let's go through the primitive types
1/7 Boolean
🔹 A Boolean type has only two values, true
and false
.
- They are mostly used for comparisons.
- See below ⬇
2/7 null
🔹 A null type contains only the null
value.
🔹 A null value means nothing, empty or unknown value.
- Note that there is an error in JavaScript. null pretends to be an object. It is NOT an object. It is a primitive type. -See below ⬇
3/7 undefined
🔹 The undefined type contains only the undefined
value.
- If a variable is declared but not assigned, then its value is undefined.
- Not that undefined is not similar to
not defined
. - See below ⬇
4/7 Number
🔹 Number type includes integers
, floating point numbers
, infinity
, -infinity
, -0
, and NaN
.
🔹 You can do Mathematical operations e.g +, -, e.t.c
- NaN means Not a Number. -See below ⬇
5/7 BigInt
🔹 This type is used to represent very large integers.
- Use cases include cryptography and financial calculation where precision is important.
- You will rarely use it.
- See below ⬇
6/7 String
🔹 A string type represents text in JavaScript
- They must be surrounded by quotes or backticks.
- See below ⬇
7/7 Symbol
🔹 The symbol type is used to create unique identifiers for objects.
- It's hard to explain them without diving deeper into objects and properties. So, we are going to skip them for now.
That's it for today. I hope you learned something. We will cover objects, arrays, and functions on their own separate blog posts.
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