javascript - Refactor var without any assignment to const in es6 -

i've following code change from

from

var httpproxy = require('http-proxy'); 

to

const httpproxy = require('http-proxy'); 

but in addition i've

var hostname; 

which defined in global scope after require modules , question should change it? if put const var hostname; think need initiation didn't before(i want change , keep behaviour ) question how recommended change it?