CODEWITHSUNDEEP
javascriptknockout.js
Sebastián Odena
Sebastián Odena

Reputation: 205

knockoutjs foreach not working in IE 9

This is a simple app simulating a chat. I provide jsfiddle:

http://jsfiddle.net/LkqTU/2785/

Some messages coming from the server, simulated by the button, and a user typing on a textarea binded to the keypress event to get te enter key and send the message.

Well, this is working fine in Chrome and Firefox but fails in IE9.

What could be wrong?

Thanks

Upvotes: 1

Views: 1265

Answers (1)

raina77ow
raina77ow

Reputation: 106453

Well, it was relatively easy to locate an error: assigning this to an external variable named self right at the beginning of Model function just doesn't look right.

The explanation why it worked fine in Chrome and Firefox, but failed in IE, though, is much more interesting. Obviously varless self refers to window.self, which is actually a special property of window object - reference to... window itself (MDN).

Internet Explorer is actually well-known for its specific treatment of this property: while in other browsers window === window.self evaluates to true, in IE it's false. And I wouldn't say IE does it without any reasoning; check this discussion for some details.

Ironically, in this particular example IE turns out to be a half-hero. ) I said "hero", because IE is the only browser that doesn't let you overwrite window.self. All the others are not so picky; add console.log(window.self) to the end of your script to witness their shame. )

And I said "half", because IE could be much more... heroic about it. ) Instead of ignoring window.self = ... line silently (and throwing an error for that far away line that used the ignored assignment in a slightly different way), why didn't IE just give an early warning? Damn, even a notice would do.

Anyway. It's pretty easy not to rely on IE's sporadic heroism for such things: just add 'use strict' line at the beginning your script, and voila! both Chrome and Firefox will spit out a 'Reference Error' warning right where it belongs - at self = this line. )

Yes, I understand that 'use strict' use is not a simple step, and it might break some scripts; yet I wholly stand by Nicholas Zakas' statement on that topic.

Upvotes: 2

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