js function 作用域

var globalVar = "I am global";

function showGlobalVar() {
    console.log(globalVar); // 输出: "I am global"
}

showGlobalVar();

function showLocalVar() {
    var localVar = "I am local";
    console.log(localVar); // 输出: "I am local"
}

showLocalVar();
console.log(localVar); // 报错: localVar is not defined

{
    let blockVar = "I am block-scoped";
    console.log(blockVar); // 输出: "I am block-scoped"
}

console.log(blockVar); // 报错: blockVar is not defined

var globalVar = "global";

function outer() {
    var outerVar = "outer";
    function inner() {
        var innerVar = "inner";
        console.log(innerVar); // 输出: "inner"
        console.log(outerVar); // 输出: "outer"
        console.log(globalVar); // 输出: "global"
    }
    inner();
}

outer();

function outer() {
    var outerVar = "I am from outer function";
    return function inner() {
        console.log(outerVar); // 输出: "I am from outer function"
    };
}

var innerFunc = outer();
innerFunc(); // 即使 outer 函数已经执行完毕，inner 函数仍然可以访问 outerVar