Ep.01: Getting Started with TS
What typescript does?
The only job Typescript does is Static checking. It analyzes the code as we write for error.
It provides many functionalities on the top of JS functionalities. It's a development tool. You can say it's a wrapper around JS.
Finally, typescript transpiles the code to JS.
Static Checking: Analyzing the code while writing and giving hints of error rather than throwing errors on execution.
Hello! TypeScript
typescript
let greetings: string = "Hello! World"; greetings = 6 //This will throw error console.log(greetings); // Hello! World
The Primitives: String, Number, and Boolean
typescript
let str: string = "I'm a string."; str = 123; // ERROR let id: number = 1236; id = fa23; // ERROR let flag: boolean = false; flag = "Hi!"; // ERROR
Typescript is smart enough to detect the type of variables on assignment. So, there's no need to write type for every variable. There's a special usecase for it.
A Red Flag - Any
TypeScript also has a special type, any, that you can use whenever you don’t want a particular value to cause typechecking errors.
Any isn't a type in TS, but is a marker in typescript to turn off type checking for a particular value wherever it's used.
noImplicitAny
When you don’t specify a type, and TypeScript can’t infer it from context, the compiler will typically default to any.
You usually want to avoid this, though, because any isn’t type-checked. Use the compiler flag noImplicitAny to flag any implicit any as an error.