问题
This my old code with VUE 2 in Tabs component:
created() {
this.tabs = this.$children;
}
Tabs:
<Tabs>
<Tab title="tab title">
....
</Tab>
<Tab title="tab title">
....
</Tab>
</Tabs>
VUE 3: How can I get some information about childrens in Tabs component, using composition API? Get length, iterate over them, and create tabs header, ...etc? Any ideas? (using composition API)
回答1:
To someone wanting whole code:
Tabs.vue
<template>
<div>
<div class="tabs">
<ul>
<li v-for="tab in tabs" :class="{ 'is-active': tab.isActive }">
<a :href="tab.href" @click="selectTab(tab)">{{ tab.name }}</a>
</li>
</ul>
</div>
<div class="tabs-details">
<slot></slot>
</div>
</div>
</template>
<script>
export default {
name: "Tabs",
data() {
return {tabs: [] };
},
created() {
},
methods: {
selectTab(selectedTab) {
this.tabs.forEach(tab => {
tab.isActive = (tab.name == selectedTab.name);
});
}
}
}
</script>
<style scoped>
</style>
Tab.vue
<template>
<div v-show="isActive"><slot></slot></div>
</template>
<script>
export default {
name: "Tab",
props: {
name: { required: true },
selected: { default: false}
},
data() {
return {
isActive: false
};
},
computed: {
href() {
return '#' + this.name.toLowerCase().replace(/ /g, '-');
}
},
mounted() {
this.isActive = this.selected;
},
created() {
this.$parent.tabs.push(this);
},
}
</script>
<style scoped>
</style>
App.js
<template>
<Tabs>
<Tab :selected="true"
:name="'a'">
aa
</Tab>
<Tab :name="'b'">
bb
</Tab>
<Tab :name="'c'">
cc
</Tab>
</Tabs>
<template/>
回答2:
This is my Vue 3 component now. I used provide to get information in child Tab component.
<template>
<div class="tabs">
<div class="tabs-header">
<div
v-for="(tab, index) in tabs"
:key="index"
@click="selectTab(index)"
:class="{'tab-selected': index === selectedIndex}"
class="tab"
>
{{ tab.props.title }}
</div>
</div>
<slot></slot>
</div>
</template>
<script lang="ts">
import {defineComponent, reactive, provide, onMounted, onBeforeMount, toRefs, VNode} from "vue";
interface TabProps {
title: string;
}
export default defineComponent({
name: "Tabs",
setup(_, {slots}) {
const state = reactive({
selectedIndex: 0,
tabs: [] as VNode<TabProps>[],
count: 0
});
provide("TabsProvider", state);
const selectTab = (i: number) => {
state.selectedIndex = i;
};
onBeforeMount(() => {
if (slots.default) {
state.tabs = slots.default().filter((child) => child.type.name === "Tab");
}
});
onMounted(() => {
selectTab(0);
});
return {...toRefs(state), selectTab};
}
});
</script>
Tab component:
export default defineComponent({
name: "Tab",
setup() {
const index = ref(0);
const isActive = ref(false);
const tabs = inject("TabsProvider");
watch(
() => tabs.selectedIndex,
() => {
isActive.value = index.value === tabs.selectedIndex;
}
);
onBeforeMount(() => {
index.value = tabs.count;
tabs.count++;
isActive.value = index.value === tabs.selectedIndex;
});
return {index, isActive};
}
});
<div class="tab" v-show="isActive">
<slot></slot>
</div>
回答3:
Oh guys, I solved it:
slots.default().filter(child => child.type.name === 'Tab')
回答4:
If you copy pasted same code as me
then just add to the "tab" component a created method which adds itself to the tabs array of its parent
created() {
this.$parent.tabs.push(this);
},
回答5:
I made a small improvement to Ingrid Oberbüchler's component as it was not working with hot-reload/dynamic tabs.
in Tab.vue:
onBeforeMount(() => {
// ...
})
onBeforeUnmount(() => {
tabs.count--
})
In Tabs.vue:
const selectTab = // ...
// ...
watch(
() => state.count,
() => {
if (slots.default) {
state.tabs = slots.default().filter((child) => child.type.name === "Tab")
}
}
)
回答6:
In 3.x, the $children property is removed and no longer supported. Instead, if you need to access a child component instance, they recommend using $refs. as a array
https://v3.vuejs.org/guide/migration/children.html#_2-x-syntax
来源：https://stackoverflow.com/questions/64154002/vue-3-how-to-get-information-about-children