報錯:ReferenceError: Cannot access 'X' before initialization
1、以下代碼報錯:ReferenceError: Cannot access 'age' before initialization
function fn (age){
if (typeof age === 'undefined'){
console.log(age);
let age = 66;
}
}
fn();
2、解決辦法:
將let換成var,let只能聲明一次