測試環境:vue v2.3.3, vue v2.3.1
案例一
父組件parent.vue
// asyncData為異步獲取的數據,想傳遞給子組件使用<template> <div> 父組件 <child :child-data="asyncData"></child> </div></template><script> import child from './child' export default { data: () => ({ asyncData: '' }), components: { child }, created () { }, mounted () { // setTimeout模擬異步數據 setTimeout(() => { this.asyncData = 'async data' console.log('parent finish') }, 2000) } }</script>子組件child.vue
<template> <div> 子組件{{childData}} </div></template><script> export default { props: ['childData'], data: () => ({ }), created () { console.log(this.childData) // 空值 }, methods: { } }</script>上面按照這里的解析,子組件的html中的{{childData}}的值會隨著父組件的值而改變,但是created里面的卻不會發生改變(生命周期問題)
案例二
parent.vue
<template> <div> 父組件 <child :child-object="asyncObject"></child> </div></template><script> import child from './child' export default { data: () => ({ asyncObject: '' }), components: { child }, created () { }, mounted () { // setTimeout模擬異步數據 setTimeout(() => { this.asyncObject = {'items': [1, 2, 3]} console.log('parent finish') }, 2000) } }</script>child.vue
<template> <div> 子組件<!--這里很常見的一個問題,就是{{childObject}}可以獲取且沒有報錯,但是{{childObject.items[0]}}不行,往往有個疑問為什么前面獲取到值,后面獲取不到呢?--> <p>{{childObject.items[0]}}</p> </div></template><script> export default { props: ['childObject'], data: () => ({ }), created () { console.log(this.childObject) // 空值 }, methods: { } }</script>created里面的卻不會發生改變, 子組件的html中的{{{childObject.items[0]}}的值雖然會隨著父組件的值而改變,但是過程中會報錯
// 首先傳過來的是空,然后在異步刷新值,也開始時候childObject.items[0]等同于''.item[0]這樣的操作,所以就會報下面的錯vue.esm.js?8910:434 [Vue warn]: Error in render function: "TypeError: Cannot read property '0' of undefined"
針對二的解決方法:
使用v-if可以解決報錯問題,和created為空問題
// parent.vue<template> <div> 父組件 <child :child-object="asyncObject" v-if="flag"></child> </div></template><script> import child from './child' export default { data: () => ({ asyncObject: '', flag: false }), components: { child }, created () { }, mounted () { // setTimeout模擬異步數據 setTimeout(() => { this.asyncObject = {'items': [1, 2, 3]} this.flag = true console.log('parent finish') }, 2000) } }</script>
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