Use fs.readFileSync instead of require.resolve and then fallback to r…

…equire.resolve if this fails.

lib/index.js

@@ -5,6 +5,8 @@
 
 var http = require('http');
 var read = require('fs').readFileSync;
+var path = require('path');
+var exists = require('fs').existsSync;
 var engine = require('engine.io');
 var client = require('socket.io-client');
 var clientVersion = require('socket.io-client/package').version;
@@ -98,11 +100,22 @@ Server.prototype.serveClient = function(v){
   this._serveClient = v;
 
   if (v && !clientSource) {
-    clientSource = read(require.resolve('socket.io-client/dist/socket.io.min.js'), 'utf-8');
-    try {
-      clientSourceMap = read(require.resolve('socket.io-client/dist/socket.io.js.map'), 'utf-8');
-    } catch(err) {
-      debug('could not load sourcemap file');
+
+    var clientSourcePath = path.resolve(__dirname, './../../socket.io-client/dist/socket.io.min.js');
+    var clientSourceMapPath = path.resolve(__dirname, './../../socket.io-client/dist/socket.io.min.js.map');
+    if(!exists(clientSourcePath)) {
+      clientSource = read(require.resolve('socket.io-client/dist/socket.io.min.js'), 'utf-8');
+    } else {
+      clientSource = read(clientSourcePath);
+    }
+    if(!exists(clientSourceMapPath)) {
+      try {
+        clientSourceMap = read(require.resolve('socket.io-client/dist/socket.io.js.map'), 'utf-8');
+      } catch(err) {
+        debug('could not load sourcemap file');
+      }
+    } else {
+      clientSourceMap = read(clientSourceMapPath);
     }
   }
 
@@ -378,7 +391,7 @@ Server.prototype.onconnection = function(conn){
 
 Server.prototype.of = function(name, fn){
   if (String(name)[0] !== '/') name = '/' + name;
-  
+
   var nsp = this.nsps[name];
   if (!nsp) {
     debug('initializing namespace %s', name);
@@ -392,7 +405,7 @@ Server.prototype.of = function(name, fn){
 /**
  * Closes server connection
  *
- * @param {Function} [fn] optional, called as `fn([err])` on error OR all conns closed 
+ * @param {Function} [fn] optional, called as `fn([err])` on error OR all conns closed
  * @api public
  */