问Nodejs如何将实时数据从Firebase发送到Angular

EN

/**
 * this is a route to call function get user By email
 */
router.get('/by/email/:email', (req,res)=>{
    //define email user
    let email = req.params.email;
    //check email param
    if(!email){ return res.status(400).json({message:'EMAILISMISSING'}) }
    //call function get user by email 
    userRef.getByEmail(email, (error,user)=>{
        if(error){ return res.status(400).json(error); }
        else{
            return res.status(200).json(user)
        }
    })
})


/**
 * this is the function bring user by email
 * @requires email
 * @returns @callback
 */
exports.getByEmail = (email,callback)=>{
    userRef.where('email','==',email)
           .get()
           .then(user=>{
                user = fb.renderMultiDocs(user);
                if(!user.length) { return callback(false,null)}
                return callback(false,user[0]);
           })
           .catch(error=>{
               return callback(error,false)
           })
}

/**
* this angular function to call by/email route and return
*/
getUserByEmail(email):any{
  return this._http.get(environment.api+'by/email/'+email)
}