for(var i=0;i<3;++i){ setTimeout(function(){ console.log(i); },100); }
js { var x = 1; let y = 1; } console.log(x); //1 console.log(y); //y is not defined!
js console.log(foo); // undefined var foo = 1; console.log(bar); // ReferenceError! let bar = 2;