Modify: Remove regex from lib/extension.js

lib/extension.js

@@ -1,20 +1,44 @@
+'use strict';
+
 var path = require('path');
 
-var EXTRE = /\.[^.]*/g;
-var LONGEXTRE = /^[.]?[^.]+([.].*[^.])$/;
+function getLongExtension(basename) {
+  if (basename[basename.length - 1] === '.') {
+    return null;
+  }
+
+  var startIndex = (basename[0] === '.') ? 1 : 0;
+
+  var dotIndex = basename.indexOf('.', startIndex);
+  if (dotIndex <= startIndex) {
+    return null;
+  }
+
+  return basename.slice(dotIndex);
+}
+
+function getPossibleExtensions(longExtension) {
+  var arr = [longExtension];
+  var len = longExtension.length;
+  var startIndex = 1;
+
+  while (startIndex < len) {
+    var dotIndex = longExtension.indexOf('.', startIndex);
+    if (dotIndex < 0) {
+      break;
+    }
+    arr.push(longExtension.slice(dotIndex));
+    startIndex = dotIndex + 1;
+  }
+
+  return arr;
+}
 
 module.exports = function(input) {
   var basename = path.basename(input);
-  var longExtension = LONGEXTRE.exec(basename);
+  var longExtension = getLongExtension(basename);
   if (!longExtension) {
     return;
   }
-  var possibleExtensions = longExtension[1].match(EXTRE);
-  /* istanbul ignore if */
-  if (!possibleExtensions) {
-    return;
-  }
-  return possibleExtensions.map(function(_, idx, exts) {
-    return exts.slice(idx).join('');
-  });
+  return getPossibleExtensions(longExtension);
 };