I need a javascript to click on a particular button automatically

I recently came across a javascript which would try to click a particular button every 20 milliseconds in amazon to buy a particular item , its this one :

setInterval(function(){ jQuery(‘.btn’).trigger(‘click’); console.log(‘Working.. Dont press any key until we add your phone to your cart.’); },10);

we are supposed to paste this in the console part of inspect element in google chrome and execute it , similarly what modifications should I make to this code so that it tries to click a particular button in whatever site I want?

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