@zimi/type-utils

typescript 类型辅助函数

$3

``
yarn add @zimi/type-utils
`

$3

PickOneOf
StructAs
Or

---

#### PickOneOf
from: https://dev.to/maxime1992/implement-a-generic-oneof-type-with-typescript-22em

` typescript
interface Group {
num: number[]
str: string[]
boo: boolean[]
}

/**
* PickOneOfGroup is {
* num: number[]
* str: undefined
* boo: undefined
* } | {
* num: undefined
* str: string[]
* boo: undefined
* } | {
* num: undefined
* str: undefined
* boo: boolean[]
* }
*/
type PickOneOfGroup = PickOneOf
`
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#### StructAs

` typescript

interface Group {
num: number[]
str: string[]
boo: boolean[]
}

/**
* StructedGroup is {
* type: 'num'
* value: number[]
* } | {
* type: 'str'
* value: string[]
* } | {
* type: 'boo'
* value: boolean[]
* }
*/
type StructedGroup = StructAs

`
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#### Or

` typescript

interface StringObj {
a: string
b: string
}

interface NumberObj {
b: number
c: number
}

function test1(input: StringObj | NumberObj) {
// error: Property 'c' does not exist on type 'StringObj'.ts(2339)
if (typeof input.c === 'number') {
console.log(input.b)
}
}

function test2(input: Or) {
if (typeof input.c === 'number') {
// correct: input.b is number
console.log(input.b)
}
}

``
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