Calculate a User's Reputation
JavaScript (ES6), 145 139 136 125 123 117 bytes

a=&gt;fetch(`//api.stackexchange.com/users?site=codegolf&amp;filter=!)LgZAmQ6ls0hH&amp;inname=`+a).then(_=&gt;_.text()).then(alert)


Saved 6 bytes thanks to Shaggy and 6 bytes thanks to Cyoce.

I'm not sure if it should output all users with the same name, or just one of them; this code outputs all of them.



f=a=&gt;fetch(`//api.stackexchange.com/users?site=codegolf&amp;filter=!)LgZAmQ6ls0hH&amp;inname=`+a).then(_=&gt;_.text()).then(alert)

f("tom")