关于JS作用域的一点小问题

    var fauxConstant = "123";

    function badFunction() {
        fauxConstant = "456";
    }

    function goodFunction() {
        var fauxConstant = "456";
    }

    function testIt() {
        alert(fauxConstant);//123
        goodFunction();
        alert(fauxConstant);//123
        badFunction();
        alert(fauxConstant);//456
    }
    testIt();