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typescript discriminated unions

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Stupid Scarab answered on March 18, 2022 Popularity 9/10 Helpfulness 2/10

answer typescript discriminated unions

related typescript unions

related typescript discriminated union

typescript discriminated unions

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// 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

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Contributed on Jun 10 2022

Stupid Scarab

0 Answers Avg Quality 2/10

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typescript unions

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type MyBool = true | false;

Popularity 8/10 Helpfulness 2/10 Language typescript

Source: www.typescriptlang.org

Tags: unions typescript un

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Contributed on Mar 18 2022

barisx

0 Answers Avg Quality 2/10

typescript discriminated union

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// 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

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Contributed on Sep 12 2023

YOU.com

0 Answers Avg Quality 2/10

typescript discriminated unions

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