调用方法看不到变量

function outer() {
    let x = 10;
    function inner() {
        console.log(x); // 可以访问
    }
    inner();
}
outer();

function test() {
    if (typeof myVar !== 'undefined') {
        console.log(myVar);
    } else {
        console.log('myVar is not defined');
    }
}

function fetchData() {
    return new Promise((resolve, reject) => {
        setTimeout(() => {
            resolve('Data fetched');
        }, 1000);
    });
}

async function getData() {
    let data = await fetchData();
    console.log(data); // 可以访问
}
getData();

function createCounter() {
    let count = 0;
    return function() {
        count++;
        console.log(count); // 可以访问
    };
}

let counter = createCounter();
counter(); // 输出 1
counter(); // 输出 2