WebFund 2015W Lecture 10: Difference between revisions

Revision as of 17:38, 4 February 2015

Resources

notes-demo code

Video

The video from the lecture given on February 4, 2015 is available now as an MP4.

Notes

CORRECTION

In lecture we saw that we could break notes-demo by giving hasOwnProperty as a username. This error is because the following code in the login post handler is incorrect:

    if (!userNotes[username]) {
	userNotes[username] = [];
    }

This code should instead say:

   if (!userNotes.hasOwnProperty(username)) {
       userNotes[username] = [];
   }

If you are treating a JavaScript object as an associative array you must explicitly check whether a given key value (property) is present using the hasOwnProperty() method inherited by every object.

Note you can create an object x with no prototype by doing the following:

@@ Line 8: / Line 8: @@
 ==Notes==
+===CORRECTION===
+In lecture we saw that we could break notes-demo by giving <tt>hasOwnProperty</tt> as a username.  This error is because the following code in the login post handler is incorrect:
+<source lang="javascript">
+    if (!userNotes[username]) {
+	userNotes[username] = [];
+    }
+</source>
+This code should instead say:
+<source lang="javascript">
+   if (!userNotes.hasOwnProperty(username)) {
+       userNotes[username] = [];
+   }
+</source>
+If you are treating a JavaScript object as an associative array you must explicitly check whether a given key value (property) is present using the hasOwnProperty() method inherited by every object.
+Note you can create an object x with no prototype by doing the following: