How to resolve 'Cross Origin domain' issue without using 'CORS' chrome extension using Javascript

[Test]

I've developed an application to access JIRA REST API. By adding 'CORS' chrome extension, I'm able to get the data from http://localhost:8000 by enabling 'CORS'

But the application doesn't work without CORS extension. 

Can someone please let me know is there a way to access the REST API without 'CORS' extension.