module: support multi-dot file extension

Support multi-dot file extensions like '.coffee.md' in Module.load.

PR-URL: https://github.com/nodejs/node/pull/23416
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: John-David Dalton <john.david.dalton@gmail.com>

1 files changed, 17 insertions, 2 deletions

diff --git a/lib/internal/modules/cjs/loader.js b/lib/internal/modules/cjs/loader.js
index 975c688eda..4a5fc596c0 100644
--- a/lib/internal/modules/cjs/loader.js
+++ b/lib/internal/modules/cjs/loader.js
@@ -219,6 +219,22 @@ function tryExtensions(p, exts, isMain) {
   return false;
 }
 
+// find the longest (possibly multi-dot) extension registered in
+// Module._extensions
+function findLongestRegisteredExtension(filename) {
+  const name = path.basename(filename);
+  let currentExtension;
+  let index;
+  let startIndex = 0;
+  while ((index = name.indexOf('.', startIndex)) !== -1) {
+    startIndex = index + 1;
+    if (index === 0) continue; // Skip dotfiles like .gitignore
+    currentExtension = name.slice(index);
+    if (Module._extensions[currentExtension]) return currentExtension;
+  }
+  return '.js';
+}
+
 var warned = false;
 Module._findPath = function(request, paths, isMain) {
   if (path.isAbsolute(request)) {
@@ -600,8 +616,7 @@ Module.prototype.load = function(filename) {
   this.filename = filename;
   this.paths = Module._nodeModulePaths(path.dirname(filename));
 
-  var extension = path.extname(filename) || '.js';
-  if (!Module._extensions[extension]) extension = '.js';
+  var extension = findLongestRegisteredExtension(filename);
   Module._extensions[extension](this, filename);
   this.loaded = true;