对不存在的变量进行对象检查以进行文档检查

Question

I have a one liner Js for Selenium tests that checks if the page is done loading.

true  === ((typeof Ext.Ajax != 'undefined' && Ext.Ajax.isLoading()) || (jQuery != 'undefined' && jQuery.active) || document.readyState != 'complete')

All other Java/Selenium ways to check are NOT compatible with our setup line of IE FF and Chrome tests (crap IE). We spent like 3 months of trying, so Selenium checks are out of question. This check is ok most of the time, except when the Extjs variable is not set in that page then i get the dreaded Ext is not defined exception and selenium crashes. Is there an another way to check for a variable in one liner which can do nested checks i tried object checks like in

javascript test for existence of nested object key

But when i do

((Ext|| {}).Ajax

I still get the exception.

Answer 1

在阅读完其余文章后，我遇到了一个解决方案：

(typeof Ext != 'undefined' ? Ext : {}) 

Answer 2

这也应该起作用：

(window.Ext || {}).Ajax