Event from parent to child component

问题

I have event that is generated in parent component and child has to react to it. I know that this is not recommended approach in vuejs2 and i have to do a $root emit which is pretty bad. So my code is this.

<template>
    <search></search>
    <table class="table table-condensed table-hover table-striped" v-infinite-scroll="loadMore" infinite-scroll-disabled="busy" infinite-scroll-distance="10">
        <tbody id="trans-table">
            <tr v-for="transaction in transactions" v-model="transactions">
                <td v-for="item in transaction" v-html="item"></td>
            </tr>
        </tbody>
    </table>
</template>

<script>
    import Search from './Search.vue';

    export default {
        components: {
            Search
        },
        data() {
            return { 
                transactions: [], 
                currentPosition: 0 
            }
        },
        methods: {
            loadMore() {
                this.$root.$emit('loadMore', {
                    currentPosition: this.currentPosition
                });
            }
        }
    }
</script>

As You can see loadMore is triggered on infinite scroll and event is being sent to child component search. Well not just search but since it's root it's being broadcast to everyone.

What is better approach for this. I know that i should use props but I'm not sure how can i do that in this situation.

回答1:

Just have a variable (call it moreLoaded) that you increment each time loadMore is called. Pass that and currentPosition to your search component as props. In Search, you can watch moreLoaded and take action accordingly.

Update
Hacky? My solution? Well, I never! ;)

You could also use a localized event bus. Set it up something like this:

export default {
    components: {
        Search
    },
    data() {
        return {
            bus: new Vue(),
            transactions: [], 
            currentPosition: 0 
        }
    },
    methods: {
        loadMore() {
            this.bus.$emit('loadMore', {
                currentPosition: this.currentPosition
            });
        }
    }
}

and pass it to Search:

<search :bus="bus"></search>

which would take bus as a prop (of course), and have a section like

created() {
    this.bus.$on('loadMore', (args) => {
        // do something with args.currentPosition
    });
}

来源：https://stackoverflow.com/questions/43256978/event-from-parent-to-child-component