Reduce regex usage.

Author: RubenVerborgh

lib/resource-mapper.js

@@ -44,7 +44,7 @@ class ResourceMapper {
     // Determine the path of an existing file
     } else {
       // Read all files in the corresponding folder
-      const filename = /[^/]*$/.exec(pathname)[0]
+      const filename = pathname.substr(pathname.lastIndexOf('/') + 1)
       const folder = `${basePath}${pathname.substr(0, pathname.length - filename.length)}`
       const files = await this._readdir(folder)
 
@@ -81,12 +81,14 @@ class ResourceMapper {
 
 // Removes a possible trailing slash from a path
 function removeTrailingSlash (path) {
-  return path ? path.replace(/\/+$/, '') : ''
+  const lastPos = path.length - 1
+  return lastPos < 0 || path[lastPos] !== '/' ? path : path.substr(0, lastPos)
 }
 
 // Removes everything beyond the dollar sign from a path
 function removeDollarExtension (path) {
-  return path.replace(/\$.*/, '')
+  const dollarPos = path.lastIndexOf('$')
+  return dollarPos < 0 ? path : path.substr(0, dollarPos)
 }
 
 // Gets the expected content type based on the extension of the path