javascript上下文

function foo(){
    console.log('foo1');
}

foo();

function foo(){
    console.log('foo2');
}

foo();

看看下面两段代码的执行结果：

var scope = "global scope";

function checkscope() {
    var scope = "local scope";

    function f() {
        return scope;
    }
    return f();
}
checkscope();

var scope = "global scope";

function checkscope() {
    var scope = "local scope";

    function f() {
        return scope;
    }
    return f;
}
checkscope()();

结果都为：local scope