TypeScript Interview Questions

TypeScript is a superset of JavaScript that compiles to plain JavaScript. It is developed and maintained by Microsoft.

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Microsoft Corporation

There are mainly two types of data types:

• Built-in: This includes number, string, boolean, void, null and undefined.
• User-defined: It includes enums, classes, interfaces, arrays, and tuple.

//Boolean
let isDone: boolean = true;

//String
let name: string = "Full Stack Tutorials";

//Number
let decimal: number = 10;

//Array
let list: number[] = [1, 2, 3, 4, 5];

//Any
let notSure: any = 5;

//Null & Undefined
let u: undefined = undefined;
let n: null = null;

1. It helps in code structuring
2. Typescript is purely object oriented programming.
3. It offers a "compiler" that can convert to JavaScript equivalent code.
4. It has a concept of namespace defined by a "module".
5. Type checking
6. Compile time error checking
7. Code completion and intelligence

1. tsc --init
2. extends in tsconfig.json
3. type vs interface
4. keyof
5. Mapped Types
6. Mixin classes
7. object vs Object
8. Transpiling async/await to ES5/ES3
9. String valued enums
10. allowJs, checkJs, // @ts-check

npm install -g typescript

tsc fileName

//Example
tsc helloworld.ts

Modules are the way to organize code in TypeScript. Modules contains classes and interfaces. It is same like namespace in C#.

Types of Modules:

1. Internal Modules
2. External Modules

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There are different types of components of TypeScript:

1. Language
2. Compiler
3. Language Service

Yes, TypeScript does support function overloading but the implementation is a bit different if we compare it to OO languages.