dependecy fix

crawler/helper/links.js

@@ -40,26 +40,6 @@ module.exports = {
     }
 };
 
-var isDomainFree = function (db, url, domain){
-    return new Promise((resolve,reject)=>{
-        http.get(url, res => {
-            res.setEncoding("utf8");
-            let body = "";
-            res.on("data", data => {
-                body += data;
-            });
-            res.on("end", () => {
-                let status = body.split(' ')[0];
-                if (status === 'free'){
-                    resolve(true);
-                }else{
-                    resolve(false);
-                }
-            });
-        });
-    });
-}
-
 var removeOccupiedDomain = function (db, url,domain){
     return new Promise((resolve,reject)=>{
         http.get(url, res => {