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.<br/>
It provides many functionalities on the top of JS functionalities. It's a development tool. You can say it's a wrapper around JS.<br/>
Finally, typescript transpiles the code to JS.
<b>Static Checking:</b> 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 - <i>Any</i>
TypeScript also has a special type, any, that you can use whenever you don’t want a particular value to cause typechecking errors.<br/> 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.