题目描述
Implement the type of just-flip-object. Examples:
Flip<{ a: "x", b: "y", c: "z" }>; // {x: 'a', y: 'b', z: 'c'}
Flip<{ a: 1, b: 2, c: 3 }>; // {1: 'a', 2: 'b', 3: 'c'}
Flip<{ a: false, b: true }>; // {false: 'a', true: 'b'}
No need to support nested objects and values which cannot be object keys such as arrays
题解
// ============= Test Cases =============
import type { Equal, Expect, NotEqual } from './test-utils'
type cases = [
Expect<Equal<{ a: 'pi' }, Flip<{ pi: 'a' }>>>,
Expect<NotEqual<{ b: 'pi' }, Flip<{ pi: 'a' }>>>,
Expect<Equal<{ 3.14: 'pi'; true: 'bool' }, Flip<{ pi: 3.14; bool: true }>>>,
Expect<Equal<{ val2: 'prop2'; val: 'prop' }, Flip<{ prop: 'val'; prop2: 'val2' }>>>,
]
// ============= Your Code Here =============
type Flip<T extends Record<PropertyKey, string | boolean | number>> = {
[P in keyof T as `${T[P]}`]: P
}
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泛型约束
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T extends Record<PropertyKey, string | boolean | number>：-
确保传入的对象
T的键是可以作为对象键的类型 -
确保传入的对象
T的值是string、boolean或number
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-
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映射类型
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[P in keyof T]：遍历对象T的所有键P -
as
${T[P]}：将值T[P]转换为字符串并作为新对象的键 -
P：将原键P作为新对象的值
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