let someVar1;
someVar1 = '123';
someVar1 = 123;

var someVar1;
someVar1 = '123';
someVar1 = 123;

let x = 0, y, z = 0;
var x = 0, y, z = 0;
for(let a = 0, b; a < 5; a++) {}

function ex() {
    let b;
}