计算属性

基础使用

import {computed} from 'vue'

// 只读
function computed<T>(
  getter: () => T,
  // 查看下方的 "计算属性调试" 链接
  debuggerOptions?: DebuggerOptions
): Readonly<Ref<Readonly<T>>>

// 可写的
function computed<T>(
  options: {
    get: () => T
    set: (value: T) => void
  },
  debuggerOptions?: DebuggerOptions
): Ref<T>

只读的计算属性

const count = ref(1)
const plusOne = computed(() => count.value + 1)

console.log(plusOne.value) // 2

plusOne.value++ // 错误

读写的计算属性

const count = ref(1)
const plusOne = computed({
  get: () => count.value + 1,
  set: (val) => {
    count.value = val - 1
  }
})

plusOne.value = 1
console.log(count.value) // 0