add doc

@@ -21,6 +21,11 @@ files.forEach((file) => {
     }
     }
 });
 });
 
 
+/**
+ * 1. origin 可接受是 正则 和 函数
+ * 2. target 可接受是 匹配字符串 和 函数
+ * @returns {Function}
+ */
 module.exports = () => {
 module.exports = () => {
     return (req, res, next) => {
     return (req, res, next) => {
         let curDomainRules = domainRules[req.subdomains[0]];
         let curDomainRules = domainRules[req.subdomains[0]];
@@ -32,6 +37,7 @@ module.exports = () => {
         for (let i = 0; i < curDomainRules.length; i++) {
         for (let i = 0; i < curDomainRules.length; i++) {
             let rule = curDomainRules[i];
             let rule = curDomainRules[i];
 
 
+            // 匹配成功
             if (
             if (
                 (_.isRegExp(rule.origin) && !_.isEmpty(rule.origin.exec(req.url))) ||
                 (_.isRegExp(rule.origin) && !_.isEmpty(rule.origin.exec(req.url))) ||
                 (_.isFunction(rule.origin) && rule.origin(req))
                 (_.isFunction(rule.origin) && rule.origin(req))
@@ -39,15 +45,21 @@ module.exports = () => {
                 let newUrl = req.url;
                 let newUrl = req.url;
 
 
                 if (_.isRegExp(rule.origin)) {
                 if (_.isRegExp(rule.origin)) {
+                    // 正则
                     if (_.isFunction(rule.target)) {
                     if (_.isFunction(rule.target)) {
+                        // 函数
                         newUrl = req.url.replace(rule.origin, _.partial(rule.target, req));
                         newUrl = req.url.replace(rule.origin, _.partial(rule.target, req));
                     } else if (_.isString(rule.target)) {
                     } else if (_.isString(rule.target)) {
+                        // 字符串
                         newUrl = req.url.replace(rule.origin, req.target);
                         newUrl = req.url.replace(rule.origin, req.target);
                     }
                     }
                 } else if (_.isFunction(rule.origin)) {
                 } else if (_.isFunction(rule.origin)) {
+                    // 函数
                     if (_.isFunction(rule.target)) {
                     if (_.isFunction(rule.target)) {
+                        // 函数
                         newUrl = rule.target(req);
                         newUrl = rule.target(req);
                     } else if (_.isString(rule.target)) {
                     } else if (_.isString(rule.target)) {
+                        // 字符串
                         newUrl = rule.target;
                         newUrl = rule.target;
                     }
                     }
                 }
                 }