Welcome to Typescript interview questions (pdf) and answers for beginners, Here are some tricky typescript interview question and answers collection which is asked in the interview. May it will help you to crack your typescript interview.
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| Typescript interview questions and answers |
1. What is namespace in Typescript? Write the declaration of the namespace.
I think Everyone familiar with the namespace of other languages, here also in TypeScript a namespace is just a collection of classes by which we can logically categories. If we want to access any class from outside of the namespace then we need to export keyword.
namespace People
{
export class Boss
{
}
export class Employee
{
}
export interface Iofficework
}
2. What is Typescript?
TypeScript is known as Object-oriented programming language developed and maintained by Microsoft. Which is provide you to optional parameters, classes, and interfaces.TypeScript is nothing but JavaScript and some additional features i.e. ES6 features. Whenever we compile the TypeScript code it first converts in JavaScript then it runs and we get output.
3.Difference between typescript and javascript?
1. Typescript is a superset of JavaScript whereas JavaScript is a scripting language.
2. Typescript has an interface concept but JavaScript havan't.
3.TypeScript doesn't run in the browser where JavaScript runs.
4.TypeScript has classes whereas JavaScript has functions.
5. Typescript support module whereas JavaScript doesn't support modules.
6. In typescript Number, a string is the interfaces whereas In, JavaScript Number, string are the Object.
4. What are the key features of typescript?
TypeScript supports different browsers or node.js versions and optimizes the resulting JavaScript. It is much easier to write clean, consistent code across a project and development team.
5.When to use a super keyword in typescript.
In typescript, Super keyword is used to reference base class properties and the base class constructor.
6.How to access static methods in TypeScript
7. What Are Classes In Typescript?
The concept of classes is very similar to .NET/Java. A Class can have constructor, member variables, properties, and methods. TypeScript also allows access to modifiers “private” and “public” for member variables and functions.
8. Tell me the command for installing typescript.
npm install -g typescript
9. What Are The Benefits Of Typescript?
TypeScript has the following benefits:
1.Intellisense
2Impose coding guidelines
3.Offers type checking
4. It helps in code structuring
5.Compile time error checking
6. Use class-based object-oriented programming
10. What is the typescript extension and how you compile?
Typescript extension is '.ts'. It is just a javascript file, when we compile typescript file, just after compilation it convert into '.js' file.
Step to compile a typescript program
1. tsc 'your typeScript File Name'
For example, to compile “program.ts”:
tsc program.ts
After compilation, you will get
program.js
11. How to declare a variable in Typescript?
var name:string="sham"
var phone:string="123456"
12. How do you declare an undefined variable?
var name:string;
var phone:int;
13. How to declare and initialize an array in Typescript?
var names:string[]; -- Declaration
names=["a","b","c","d"] -- Initialization
14. How to achieve inheritance in Typescript?
15. How to make a module in Typescript?
https://johnpapa.net/typescriptpost4/
16. What is the role of constructor in Typescript?
A constructor is responsible for initializing the variable of the class.
17. How to initialize the static variables?
class office
{
static phoneNo:number=101;
}
office.phoneNo=106;
console.log(office.phoneNo) ;
18. What is the difference between var and let in Typescript?
1.var declaration done at function scoped and let declaration done at block scoped.
2.var allow you to re-declare the same variable in the same scope. whereas let will not
19.How to define a global variable in a typescript module.
https://github.com/Microsoft/TypeScript/issues/18237
20.How to export a variable.
export var demo = [1,2,3];
21. What is the role of var keyword in typescript?
var is key it helps us to create an object of a class.
22. How to Convert string to number in TypeScript?
name:string;
empcode:number;0
//convert string to number
this.empcode = Number(name);
23. Can we debug Typescript file?
Yes, With the help of .js source map file.
24. What are the classes in TypeScript?
Typescript class is very similar to other languages like (.Net, Java). As we know that class can have constructor, member, variable and methods.
25. What are the benefits of Typescript?
1. ES7 and ES6 Features support.
2. User-friendly for Java and .Net programmer.
3. Intellisense.
4. Object-Oriented programming support.
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