Why does require cause a timeout in Internet Explorer 9 when the browser console isn’t open?

Question

I am maintaining a legacy web application that is built on top of the following stack:

• Server side
  • NGINX
  • Tornado
• Client side
  • RequireJS
  • jQuery
  • Backbone

Everything works fine in Firefox and Chrome, but in IE9, calling require inside a function to dynamically load a module causes a timeout. With the JavaScript console opened to look for errors it works fine (and there are no errors logged).

Any ideas?

Answer 1

Activated developer tools usually affect your page and javascript with at least two things:
1) console.*() functions are available while dev tools are open (usually it's because of forgotten console.log() in your code. I recommend console.log wrapper)
2) different than default IE rendering engine version selected. Check your Doctype and X-UA-Compatible meta tag value.

Also check this: Does IE9 enable 'something' when using developer tools?