2 - ref 全家桶

[MioFeatherDust]

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

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

// Challenge 1: Update ref
function update(value:number) {
  // 直接赋值
  count.value = value
}

/**
 * Challenge 2: Check if the `count` is a ref object.
 * Make the output be 1
*/
// 判断类型与对象中是否有value值
function isRef<T>(value: unknown): value is Ref<T> {  
  return value && typeof value === 'object' && 'value' in value;  
}  

console.log(  
  isRef(count) ? 1 : 0  
);  

/**
 * Challenge 3: Unwrap ref
 * Make the output be true
*/
function initialCount(value: number | Ref<number>) {
  // Make the output be true
  if(isRef(value)){
    value = value.value
  }
  console.log(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,
})
//计算属性双向绑定
const fooRef = computed({  
  get: () => state.foo,  
  set: (newValue) => (state.foo = newValue),  
});  
// mutating the ref updates the original
fooRef.value++
console.log(state.foo === 2)

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

</script>