Breaking News: Grepper is joining You.com. Read the official announcement!

typescript discriminated union

Add Answer

YOU.com answered on April 24, 2021 Popularity 8/10 Helpfulness 2/10

answer typescript discriminated union

related typescript discriminated unions

related typescript union

typescript discriminated union

Comment

// Example of a discriminated union in TypeScript
interface Square {
  kind: "square";
  sideLength: number;
}

interface Circle {
  kind: "circle";
  radius: number;
}

type Shape = Square | Circle;

function calculateArea(shape: Shape): number {
  switch (shape.kind) {
    case "square":
      return shape.sideLength ** 2;
    case "circle":
      return Math.PI * shape.radius ** 2;
    default:
      throw new Error("Invalid shape");
  }
}

const square: Square = {
  kind: "square",
  sideLength: 5
};

const circle: Circle = {
  kind: "circle",
  radius: 3
};

console.log(calculateArea(square)); // Output: 25
console.log(calculateArea(circle)); // Output: 28.274333882308138

Popularity 8/10 Helpfulness 2/10 Language typescript

Source: Grepper

Link to this answer
Share Copy Link

Contributed on Sep 12 2023

YOU.com

0 Answers Avg Quality 2/10

Closely Related Answers

typescript discriminated unions

Comment

// Object unions with variants of a similiar property, but different
// key names. Need to add a common property to connect them.
interface Circle {
  kind: "circle";
  radius: number;
}
 
interface Square {
  kind: "square";
  sideLength: number;
}
 
type Shape = Circle | Square;

// TypeScript can now narrow out the members
function getArea (shape: Shape) {
  if (shape.kind === "circle") {
    return Math.PI * shape.radius ** 2 // safely accessing shape.radius
  }
}

// Alternatively use a switch statement
switch(shape.kind) {
  case 'circle':
    return Math.PI * shape.radius ** 2
  case 'square':
    return shape.sideLength ** 2

Popularity 9/10 Helpfulness 2/10 Language typescript

Source: Grepper

Tags: typescript t

Link to this answer
Share Copy Link

Contributed on Jun 10 2022

Stupid Scarab

0 Answers Avg Quality 2/10

typescript union

Comment

type Circle = { kind: 'circle'; radius: number };
type Rect = { kind: 'rect'; width: number; height: number };
type Shape = Circle | Rect;

function getArea(shape: Shape) {
    return shape.kind === 'circle' ? 
        Math.PI * shape.radius ** 2
        : shape.width * shape.height;
}

Popularity 9/10 Helpfulness 1/10 Language typescript

Source: dev.to

Tags: typescript t

Link to this answer
Share Copy Link

Contributed on Jan 10 2023

haya huang

0 Answers Avg Quality 2/10

typescript union

Comment

// Union Type: function reacts depending on x type (array of string OR string)
function welcomePeople(x: string[] | string) {
  if (Array.isArray(x)) {
    console.log("Hello, " + x.join(" and "));  		// 'x' is 'string[]'
  } else {										
    console.log("Welcome lone traveler " + x);		// 'x' is 'string'
  }
}

Popularity 10/10 Helpfulness 1/10 Language typescript

Source: www.typescriptlang.org

Tags: typescript t

Link to this answer
Share Copy Link

Contributed on Apr 24 2021

VasteMonde

0 Answers Avg Quality 2/10

typescript discriminated union

Contents

More Related Answers

typescript discriminated union

Closely Related Answers

typescript discriminated unions

typescript union

typescript union

Grepper

Documentation

Social

Legal

Contact

Oops, You will need to install Grepper and log-in to perform this action.