b组件

<view class="">{{wife}}</view>

    export default {
        name:"b",
        data() {
            return {
                num:0,
                wife:'小红'
            };
        },
        created() {
            uni.$on('upnum',(num)=>{//注册全局事件
                this.num +=num
            }),
            uni.$on('wi',(wife)=>{//注册全局事件
                this.wife =wife
            })
        }
    }

a组件:

<button type="default" @click="addNum">a让b++</button>
<button type="default" @click="changewi">改变b的wife</button>

export default {
        name:"a",
        data() {
            return {
                wife:'桂明明'
            };
        },
        methods:{
            addNum(){
                uni.$emit('upnum',10) //$emit()调用就好了
            },
            changewi(){
                uni.$emit('wi','桂明明')
            }
        }
    }