Vue.js: Difference between revisions
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| Line 7: | Line 7: | ||
* 缺點 | * 缺點 | ||
** 連動事件時, 當下的值還在未變更狀態 | ** 連動事件時, 當下的值還在未變更狀態 | ||
** 連動事件時, | ** 連動事件時, 如果再次引用 computed 數值會發生 function loop | ||
<source lang="js"> | <source lang="js"> | ||
computed: { | computed: { | ||
lifeCycleState () { | lifeCycleState () { | ||
this.onChangeState() | |||
return this.value | return this.value | ||
} | } | ||
Revision as of 08:43, 30 June 2021
Child 偵測 Parent 數值變化方法
computed in child
- 缺點
- 連動事件時, 當下的值還在未變更狀態
- 連動事件時, 如果再次引用 computed 數值會發生 function loop
computed: {
lifeCycleState () {
this.onChangeState()
return this.value
}
}
watcher in child
- 缺點
- 如果對象是 property, 需要 immediate: true
- 如果對象是 property, oldVal 一定是 undefined, 無法取得上一個 tick 的值
- 如果對象是物件, 需要 deep: true, 但是效能會大幅下降
watcher: {
foo: {
handler: (newVal, oldVal) {
// ...
},
immediate: true,
deep: true
}
}