Final thoughts
Ext JS 5 is a nice and powerful framework that can make powerful applications with no hard work. Worldwide, it's one of the most powerful frameworks for application development, and it will continue to be so for a long time. However, the tool will not do the work itself. We need to plan, design accurately, and understand how this framework works things out, so that it can make life easier for us and also speed up the development process.
As an example, you can combine other libraries, such as jQuery, with the same application. The trick is that you need to test and understand how these, being combined on the same application or web page, can coexist without conflicting with each other.
Note
Although, it is possible to use Ext JS and jQuery, it's not recommended to combine both, because Ext JS classes can produce the same functionality and results. So, there is no need to mix them, unless it's imperative for your project.