typescript 類型/對象的條件屬性

Question

假設我有一個看起來像這樣的配方成分類型

export type RecipeIngredient = {
  name: string;
  quantity: Number | string;
  measurement: "grams" | "mililitres" | "custom";
};

例子

const potatoes: RecipeIngredient = { name: 'potatoes', quantity: 100, measurement: 'grams' }

這很好，但我也希望僅在自定義測量時將數量作為字符串。 這可能嗎？

正確的例子

const rosemary: RecipeIngredient = { name: 'rosemary', quantity: 'a handful', measurement: 'custom' }

我想要無效的

const fish: RecipeIngredient = { name: 'fish', quantity: '100g', measurement: 'grams' }

Answer 1

export type RecipeIngredient = {
  name: string;
  quantity: Number;
  measurement: "grams" | "mililitres";
} | {
  name: string;
  quantity: string;
  measurement: "custom";
};