Why do I get an error when I use var outside? You won"t make a mistake in it?
function fn(x=8){
var x = 89;
console.log(x);//
}
fn();
let y = 7;
var y = 8;//
function fn(x=8){
var x = 89;
console.log(x);//
}
fn();
let y = 7;
var y = 8;//function are equivalent to the variables from var. The repeated definition of var will not report an error
because on the outside
you declare y
you declare y
if you declare y with var
let/const forbids variable promotion
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