Interfaces define structure, types are more flexible.

TypeScript Interfaces - Learn TYPESCRIPT | Revochamp

Name: TypeScript Interfaces
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Author: Revochamp

What is an Interface?

An interface in TypeScript defines the structure of an object, specifying the properties and their types.

Basic Example

TypeScriptRead-only

interface User {
  name: string;
  age: number;
}

let user: User = {
  name: 'John',
  age: 30
};

interface User {
  name: string;
  age: number;
}

let user: User = {
  name: 'John',
  age: 30
};

Optional Properties

TypeScriptRead-only

interface User {
  name: string;
  age?: number;
}

interface User {
  name: string;
  age?: number;
}

Readonly Properties

TypeScriptRead-only

interface User {
  readonly id: number;
}

interface User {
  readonly id: number;
}

Function Interface

TypeScriptRead-only

interface AddFn {
  (a: number, b: number): number;
}

interface AddFn {
  (a: number, b: number): number;
}

Extending Interfaces

TypeScriptRead-only

interface Person {
  name: string;
}

interface Employee extends Person {
  salary: number;
}

interface Person {
  name: string;
}

interface Employee extends Person {
  salary: number;
}

Interface vs Type

Feature	Interface	Type
Extendable	Yes	Yes
Object Shape	Yes	Yes
Union Types	No	Yes

Best Practices

Use interfaces for object structures
Use meaningful names
Keep interfaces small and reusable
Use extension for scalability

Common Mistakes

Overcomplicating interfaces
Using any type inside interfaces
Not reusing interfaces
Confusing interface with type

Conclusion

Interfaces help enforce structure and improve maintainability in TypeScript applications.

Feature

Interface

Type

Extendable

Yes

Object Shape

Yes

Union Types

Yes

TypeScript Interfaces

TypeScript Interfaces

What is an Interface?

Basic Example

Optional Properties

Readonly Properties

Function Interface

Extending Interfaces

Interface vs Type

Best Practices

Common Mistakes

Conclusion

Try it yourself

Test Your Knowledge

Frequently Asked Questions

Need help?

TypeScript Interfaces

TypeScript Interfaces

What is an Interface?

Basic Example

Optional Properties

Readonly Properties

Function Interface

Extending Interfaces

Interface vs Type

Best Practices

Common Mistakes

Conclusion

Try it yourself

Test Your Knowledge

Frequently Asked Questions

Need help?