想實(shí)現(xiàn)前端發(fā)送注冊(cè)的賬號(hào)密碼數(shù)據(jù)通過Post請(qǐng)求給后臺(tái)，但是后臺(tái)該咋寫啊。我一點(diǎn)注冊(cè)，它就提示報(bào)錯(cuò)說“Cannot POST /”這是我的vue.js前端代碼register(){            if(this.username == ''|| this.password == ''){                 alert('請(qǐng)輸入用戶名或密碼')             }else{                 let data = {'username':this.username,'password':this.password}                this.$axios.post('/register/qian',data)                 .then((res)=>{                     console.log(res)                    this.$router.push('register')                 })                              }         }這是node.js后臺(tái)的，用了express 和 mongooserouter.post('/register/qian',function(req,res){req.on('data',function(data){     obj=JSON.parse(data)    console.log(obj)     res.send('數(shù)據(jù)已接受') })})