javascript - 删除重复的错误处理代码Node.js

Question

我的Node.js代码中有重复的错误处理代码，如何才能更好地摆脱重复的代码。我特别想询问有关此回调方式而不是Promise方式的错误处理。

var request = require('request');
var URL = 'http://localhost:3000';

var getRanking = function get_rank(error, response, body) {
   if (error) {
        handleError(error);
   } else {         
       if (response.statusCode != 200) {
          handleError(response);
       } else {        
          console.log('Response 1 ' + body);
          request(URL + '/iso/country/' + JSON.parse(body).Country, getISO);
       }
   }
}

var getISO = function get_iso(error, response, body) {
    if (error) {
         handleError(error);          
    } else {
        if (response.statusCode != 200) {
             handleError(response)
        } else {
             console.log("Response 2 "+body);
             request(URL+'/olympic/2016/medal/'+JSON.parse(body).iso,getMedalCount);
        }
    } 
}

var getMedalCount = function get_medal_count(error, response, body) {
    if (error) {
       handleError(error);
    } else {
       if (response.statusCode != 200) {
           handleError(response);
       } else {        
           console.log("Response 3 " + body);
       }
    }  
}

function handleError(err) {
   console.log('Error ' + JSON.stringify(err))
}

request(URL+'/olympic/2016/ranking/4', getRanking);

Answer 1

创建一个功能handleResponse，并在该功能中编写response handling duplicated code。

按照给定的function调用该required parameters，

var request = require('request');
var URL = 'http://localhost:3000';

var getRanking = function get_rank(error, response, body) {
   handleResponse(error, response, body, 'getISO');
}

var getISO = function get_iso(error, response, body) {
    handleResponse(error, response, body, 'getMedalCount');
}

var getMedalCount = function get_medal_count(error, response, body) {
    handleResponse(error, response, body null);
}

function handleResponse(error, response, body, url) {
   if (error) {
        handleError(error);
   } else {         
       if (response.statusCode != 200) {
          handleError(response);
       } else {
            if(url == 'getISO')        
            {
                request(URL + '/iso/country/' + JSON.parse(body).Country, getISO);
            }
            else if(url == 'getMedalCount')
            {
                request(URL+'/olympic/2016/medal/'+JSON.parse(body).iso,getMedalCount);
            }
       }
   }
}

function handleError(err) {
   console.log('Error ' + JSON.stringify(err))
}

request(URL+'/olympic/2016/ranking/4', getRanking);