2 - ref 全家桶

[sly3464]

<script setup lang="ts">
import { ref, Ref, reactive, isRef, unref, toRef, } from "vue"

const initial = ref(10)
const count = ref(0)

// Challenge 1: Update ref
function update(value) {
  // impl...
  count.value = value
}

/**
 * Challenge 2: Check if the `count` is a ref object.
 * Make the output be 1
*/
console.log(
  // impl ? 1 : 0
  isRef(count) ? 1 : 0
)

/**
 * Challenge 3: Unwrap ref
 * Make the output be true
*/
function initialCount(value: number | Ref<number>) {
  value = unref(value) 
  // Make the output be true
  console.log('value === 10\n',value === 10)
}

initialCount(initial)

/**
 * Challenge 4:
 * create a ref for a property on a source reactive object.
 * The created ref is synced with its source property:
 * mutating the source property will update the ref, and vice-versa.
 * Make the output be true
*/
const state = reactive({
  foo: 1,
  bar: 2,
})
const fooRef = toRef(state,"foo") // change the impl...

// mutating the ref updates the original
fooRef.value++
console.log('state.foo === 2\n',state.foo === 2)

// mutating the original also updates the ref
state.foo++
console.log('fooRef.value === 3\n',fooRef.value === 3)

</script>

<template>
  <div>
    <p>
      <span @click="update(count - 1)">-</span>
      {{ count }}
      <span @click="update(count + 1)">+</span>
    </p>
  </div>
</template>