js的变量作用域

function query() {
        var a = 1;
        for (var i = 0; i < 10; i++) {
            var b = i;
        }
        return b + a;
    }
    var q = query();
    alert(q);//  9 + 1 =  10

function test() {
        var a= ‘a‘, b = [];
        b.push(a);
        try {
            throw ‘exception‘;
        } catch (e) {
            a = ‘c‘;
        }
        b.push(a);
        return b;
    }
    alert(test());//a,c