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let

  • let
let x = 1;

console.log(x);      // 1

if (true) {
    console.log(x);  // 1
    x = 2;
    console.log(x);  // 2
}
console.log(x);      // 2

let x = 1;

console.log(x);      // 1

if (true) {
    //console.log(x);  // ReferenceError: x is not defined
    let x = 2;
    console.log(x);  // 2
}
console.log(x);      // 1