TypeScript is everywhere in modern web development. It isn't a different language so much as JavaScript with safety checks added.
Direct answer
TypeScript is JavaScript with a type system. You describe what kind of value each variable or function expects, and TypeScript warns you about mistakes before the code runs, then compiles to plain JavaScript. Learn JavaScript first, then add TypeScript when you start larger projects.
Example
// JavaScript: runs, then fails or gives an odd result
function double(n) {
return n * 2;
}
double("five"); // NaN
// TypeScript: caught before running
function double(n: number): number {
return n * 2;
}
double("five"); // Error: Argument of type 'string' is not assignable to parameter of type 'number'
Key differences
| JavaScript | TypeScript | |
|---|---|---|
| Types | Checked while running | Checked before running |
| Setup | Runs in the browser | Needs a compile step |
| Mistakes | Found later | Many caught early |
| Learning curve | Gentler | Extra concepts |
| Large projects | Harder to maintain | Easier to maintain |
Pros and cons of TypeScript
Pros: fewer bugs, better editor help, clearer code in teams.
Cons: extra tooling, more to learn, sometimes more typing.
Which to learn first
JavaScript. See JavaScript for beginners. Once you're comfortable, move on to the TypeScript tutorial for beginners.
In practice
Many teams use TypeScript for web apps and libraries. Plain JavaScript is still common for small scripts and learning.
Where Teyro fits
Teyro's TypeScript for Beginners course adds types step by step in short lessons. Learn the language first in JavaScript for Beginners. Both are free to start.
The bottom line
JavaScript first, TypeScript next.
