RuntimeGuard

自 1.2.0 起

定义运行时类型检查的类型守卫函数。

签名

type RuntimeGuard<T> = (value: unknown) => value is T

参数

参数	描述
T	要守卫的类型

示例

基本用法

import type { RuntimeGuard } from 'uni-types'

const isString: RuntimeGuard<string> = (value): value is string =>
  typeof value === 'string'

const isNumber: RuntimeGuard<number> = (value): value is number =>
  typeof value === 'number'

对象类型守卫

interface User {
  name: string
  age: number
}

const isUser: RuntimeGuard<User> = (value): value is User => {
  return typeof value === 'object' && value !== null &&
    'name' in value && 'age' in value &&
    typeof (value as User).name === 'string' &&
    typeof (value as User).age === 'number'
}

在函数中使用

function processValue(value: unknown, guard: RuntimeGuard<string>) {
  if (guard(value)) {
    // value 现在被类型为 string
    console.log(value.toUpperCase())
  }
}

相关

• GuardedType - 从守卫提取类型
• AssertionFunction - 断言函数类型