Ported client side API calls from sync to async

Fixes (#36 )

I Have ported client Side API calls from sync to async.
Initially, There was a warning -
Synchronous XMLHttpRequest on the main thread is deprecated because of its detrimental effects to the end user's experience. For more help, check https://xhr.spec.whatwg.org/.
This warning has been fixed now !!

Testing - I have tested this locally, and it works fine.

Changes done in :- eventPage.js and sss.js

Note -

I wanted to point out some issues, I was wondering why in eventPage.js ,
inside checkWebsite function : 1964 is used, when there are a total of 1989 keys in the news_websites.json.

In the above PR I have set -

len_domain_list = Object.keys(domainsList).length;, and used it to iterate till the last key.

I'll also attach the screenshots for reference-

Original:

Actual number of Keys: