为什么我的状态值总是未定义？

let myState; // 声明变量
myState = 'someValue'; // 赋值

function setState() {
    let myState = 'someValue';
}

console.log(myState); // 报错，myState is not defined

let myState;

function setState() {
    myState = 'someValue';
}

setState();
console.log(myState); // 输出: someValue

async function fetchData() {
    let response = await fetch('https://api.example.com/data');
    let data = await response.json();
    return data.state;
}

let myState;
fetchData().then(state => {
    myState = state;
    console.log(myState); // 输出: 获取到的状态值
});

let obj = {};
obj.state = 'someValue';

if (obj.state) {
    console.log(obj.state); // 输出: someValue
} else {
    console.log('State is undefined');
}

let myState;

function initializeState() {
    myState = 'initialized';
}

function printState() {
    if (myState !== undefined) {
        console.log(myState);
    } else {
        console.log('State is undefined');
    }
}

initializeState();
printState(); // 输出: initialized