add comment

@@ -8,6 +8,7 @@ const captchaService = require('../models/captcha-service');
 const helpers = global.yoho.helpers;
 const CAPTCHA = 'yoho4946abcdef#$%&!@';
 
+// 对比函数
 const _mustEqual = (req) => {
     return req.body.verifyCode === req.session.captcha ||
         req.body.verifyCode === CAPTCHA;
@@ -78,6 +79,7 @@ const generate = (req, res, next) => {
     }).catch(next);
 };
 
+// 端到端检查
 const checkAPI = (req, res) => {
     let count = req.session.captchaCount;