TypeScript interview questions
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Start with practicing the questions below. Whether a question involves multiple choice or live coding, we will give you hints as you go and tell you if your answers are correct or incorrect.
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1. Color Type
TypeScript Arrays OOP Public New
TypeScript
The TypeScript programming language is a strict superset of JavaScript. It adds optional static typing and class-based object-oriented programming to the language
Arrays
An array is a container of a fixed number of objects of a similar type. It is a fundamental component of most programming languages.
OOP
Object-oriented programming is a paradigm based on encapsulating logic and data into objects, which may then contain fields and procedures. Many of the most widely used programming languages are based on OOP, making it a very important concept in modern programming.
Public
Public questions (free plan) are common interview questions. They are great for practicing, or if you want to filter candidates using the classic problems.
The following code initialises three types representing the colors: red, green and blue.
type ColorType = [string, number, number, number]; let red: ColorType = ['Red', 1, 0, 0]; let green: [string, number, number, number] = ['Green', 0, 1, 0]; let blue = ['Blue', 0, 0, 1];
Select all the statements that are correct.
Easy
2min
2. Uppercase Types
TypeScript Language features OOP Public
TypeScript
The TypeScript programming language is a strict superset of JavaScript. It adds optional static typing and class-based object-oriented programming to the language
Language features
Knowing the most important features of a programming language is necessary for the effective use of many parts of the framework as well as keeping the code readable.
OOP
Object-oriented programming is a paradigm based on encapsulating logic and data into objects, which may then contain fields and procedures. Many of the most widely used programming languages are based on OOP, making it a very important concept in modern programming.
Public
Public questions (free plan) are common interview questions. They are great for practicing, or if you want to filter candidates using the classic problems.
The following code initializes strings as three different types and attempts to make them uppercase. Which statements about the behavior of the typescript compiler are correct?
let stringType: string = "string type"; stringType.toUpperCase(); let anyType: any = "any type"; anyType.toUpper(); anyType.toUpperCase(); let objectType: Object = "object type"; objectType.toUpperCase();
Easy
2min
3. Positionable
TypeScript Mixins OOP Public New
TypeScript
The TypeScript programming language is a strict superset of JavaScript. It adds optional static typing and class-based object-oriented programming to the language
Mixins
Mixins are a design pattern that allows classes to be built up from a number of reusable components by combining simpler partial classes. As an increasingly popular design pattern it's important for developers to understand.
OOP
Object-oriented programming is a paradigm based on encapsulating logic and data into objects, which may then contain fields and procedures. Many of the most widely used programming languages are based on OOP, making it a very important concept in modern programming.
Public
Public questions (free plan) are common interview questions. They are great for practicing, or if you want to filter candidates using the classic problems.
Consider the following two base classes, Positionable and Rotatable, and MovingObject derived class:
class Positionable {
locationX: number;
locationY: number;
}
class Rotatable {
orientation: number;
rotate(orientation: number) {
this.orientation += orientation;
}
align(rotatable: Rotatable) {
this.orientation = rotatable.orientation;
}
}
class MovingObject implements Positionable, Rotatable {
locationX: number = 0;
locationY: number = 0;
orientation: number = 0;
rotate: (orientation: number) => void;
}
applyMixins(MovingObject, [Positionable, Rotatable]);
function applyMixins(derivedCtor: any, baseCtors: any[]) {
baseCtors.forEach(baseCtor => {
Object.getOwnPropertyNames(baseCtor.prototype).forEach(name => {
derivedCtor.prototype[name] = baseCtor.prototype[name];
});
});
}
let mover = new MovingObject();
mover.rotate(30);
Select all the statements that are correct.
Hard
3min
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