js 回调函数的用法

简单例子:

function add(num1, num2, callback) {
            var sum = num1 + num2;
            callback(sum);
        }
         
         
        add(1, 2, function (sum) {
            console.log(sum); //=>3
        }

vue 中用法:

methods: {
up(callback){
                uni.uploadFile( {
                    url: 'api/common/upload',
                    filePath: this.USERINFO.avatar,
                    name: 'file',
                    header: {
                      'token': uni.getStorageSync('token')
                    },
                    success: (res) => {
                        // 
                        let data = JSON.parse(res.data)
                        // console.log(data,990000)
                        let a = data.data.fullurl
                        // console.log(that.USERINFO.avatar,990000)
                        
                            // uni.setStorageSync('USERDATA',this.USERINFO)
                            // callback(this.USERINFO.avatar)
                             // console.log(this.USERINFO.avatar,33333)
                        callback(a)
                    }
                })
                
            },

async formSubmit(){
　　

await this.up( async(dataStatus) => {
        console.log(dataStatus,999)
let param = {
username:this.USERINFO.username,
avatar:dataStatus,
mobile:this.USERINFO.mobile,
}
const { data } = await this.$api.user.settingsInfo(param)
if(data.code == 1){
this.$refs.uToast.show({
title: data.msg,
type: 'success'
})
uni.setStorageSync('USERDATA',this.USERINFO)
this.initData()
console.log(data,90906767);
}else{
this.$refs.uToast.show({
title: data.msg,
type: 'error'
})
}


    })

　　

}

},