javascript - Confused about let in for loop in ES6?

Question

As shown in the picture above, it shows that i has been declared, that is, it cannot be declared repeatedly; while in the picture below But it can be re-declared using let, why?

Answer 1

Why can let be repeated? Icon

---

Why do let statements conflict with var statements? First, the var statement will be promoted to the top of the current function, that is, the order is as follows:

1. var i

2. This is the beginning of the for loop

3. Just started parsing let i = 0 --->Error report
   Look at the picture again

Answer 2

<code>// for是一个区块，内部又是一个小区块，你的代码可以简写为
{
    let i = 0;  // i作用于这个大区块
    {
        var i = 'abc';  // 此处的i也作用于这个大区块
        console.log(i);
    }
}

{
    let i = 0; // i作用于这个大区块
    {
        let    i = 'abc'; // i作用于这个小区块
        console.log(i);
    }
}

// 如果你这么写是可以的
for (var i = 0; i < 3; i++) {
    let i = 'abc';
    console.log(i);
}
// 简写
{
    var i = 0; // i作用于这个大区块
    {
        let    i = 'abc'; // i作用于这个小区块
        console.log(i);
    }
}</code>