This content originally appeared on DEV Community and was authored by Karandeep Singh
Today! We’re going to continue TypeScript learning like you’re a smart 5-year-old who loves to build things and asks “why?” (which is the best thing ever).
& yes “why?” is my way of learning.
I’ve divided this into 20 Chapters. and will go one by one and each will be of 2 – 3 min. of read.
This is a Continuation. if you have not read the Previous chapter – Chapter 7
Chapter 8: Literal Types – “Exactly This”
(aka: “this one exact thing.”)
Imagine This:
You tell your friend:
“Bring me a juice.”
They bring Berries 
, Peach 
, or orange 
because you did not specify which one to bring.
Now you say:
“Bring me exactly orange juice.”
Now there’s zero confusion.
What are Literal Types?
They let you specify exactly what value is allowed instead of just “any string” or “any number.”
Example:
let direction: "left" | "right" | "up" | "down";
direction = "left"; // ✅
direction = "jump"; // ❌ Error! Not allowed
This says:
“direction can only be one of these exact strings.”
Real World Example
let diceRoll: 1 | 2 | 3 | 4 | 5 | 6;
diceRoll = 3; // ✅
diceRoll = 7; // ❌ Error!
Combined with type aliases:
type Theme = "light" | "dark";
let currentTheme: Theme = "light";
Why is this powerful?
- It helps enforce exact values in APIs, configurations, UI options, etc.
- Makes your app safer by restricting invalid values.
- Helps with auto-suggestions in your preffered IDE.
Read Previous Chapters
If you enjoyed this and want to master TypeScript and other technologies, follow the series and drop a like!
I’m a passionate software developer sharing the cool things I discover, hoping they help you level up on your coding journey.
How i created my own State Management Library : Rethinking State Management in React — From a Dev, for Developers.
This content originally appeared on DEV Community and was authored by Karandeep Singh