解决vue.js this.$router.push无效的问题

login() {
  if(this.email.length > 0 && this.password.length >0) {
   this.$http.post('/api/login', {
    user: this.email,
    password: this.password
   })
   .then(res => {
    let userPwd = res.data
    if(this.password == userPwd) {
     this.$router.push("/")
    } else {
     alert("错误，请重新输入！")
    }
   })
   .catch(err => {
    console.log(err)
   })
  } else {
   alert("输入错误！")
  }
  }

login() {
 const self = this;
 if(this.email.length > 0 && this.password.length >0) {
  this.$http.post('/api/login', {
   user: this.email,
   password: this.password
  })
  .then(res => {
   let userPwd = res.data
   if(this.password == userPwd) {
    self.$router.push("/")
   } else {
    alert("错误，请重新输入！")
   }
  })
  .catch(err => {
   console.log(err)
  })
 } else {
  alert("输入错误！")
 }
 }