Why console.log('hello world'); undefined?

Question

Google Chrome

https://www.olx.ua/nedvizhimost/lvov/
gives
> console.log('hello world');
<- undefined
why?
UPD : apparently on the website
console.log = function(){};
the second question is how to get the console back?
UPD :
figured it out)) when building the DOM
CT = console
window.onload = function()
{
console = CT;
}