how to get google search url as reference url in javascript?

how to get google search url as reference url in javascript?

i'm creating a project which needs the keywords from search engines to
show users.
i have tried document.referrer but it shows only referrer domain.
if user searches like "buy a pc" then this url is generating by google
https://www.google.com/search?q=buy+a+pc&oq=buy+a+pc&aqs=chrome..69i57j5j0l2j69i61.1674j0&sourceid=chrome&ie=UTF-8#psj=1&q=buy+a+pc
now i need this url when user choose the my website or my site page from
google results to extract keywords from url but i have to do this by
javascript only.
Thanks.