check for undefined as well as null

jiakuan · Oct 8, 2012 · b418793 · b418793
1 parent c41f79e
commit b418793
Showing 1 changed file with 3 additions and 4 deletions.
diff --git a/lib/linked_list.js b/lib/linked_list.js
@@ -10,21 +10,20 @@ LinkedList.prototype = {
 LinkedList.prototype.append = function(node) {
   if (typeof this.first === 'undefined' || this.first === null) {
     this.first = node;
-    this.last = node;
   } else {
-    node.prev = this.last;
     node.next = null;
     this.last.next = node;
-    this.last = node;
   }
+  node.prev = this.last;
+  this.last = node;
   this.length++;
 };
 
 LinkedList.prototype.insertAfter = function(node, newNode) {
   newNode.prev = node;
   if (node) {
     newNode.next = node.next;
-    if (typeof node.next !== 'undefined' && node.next !== null) {
+    if (typeof node.next != 'undefined' && node.next !== null) {
       node.next.prev = newNode;
     }
     node.next = newNode;