如何将复选框中所选值的值与数字进行比较

Question

我必须将复选框中所选值的值与我从json获得的数字数据进行比较。

var multiQ= new Array();
var questionIndex = 0;
var grade=0;

function updateQuestion(direction) {
    questionIndex += direction;
    if (questionIndex <multiQ.length && questionIndex >= 0) {
        $("#question").html(multiQ[questionIndex].question);
        $('#answers').empty();
        $.each(multiQ[questionIndex].answers, function(key, val) {
            $('#answers').append('<label><input type="checkbox" value="key" id="checkboxid" onchange="test(this)" >' + val + '</label>');
            console.log(typeof(val));

        });
        console.log(multiQ[questionIndex].correct_a);     
    }
    else {
        questionIndex -= direction;
    }
} 
function test() {
                $('input:checked').each(function () {
                    console.log("grade");
                    if (this.value == multiQ[questionIndex].correct_a) {
                        grade=+1;

                    }
                });
            };

测试功能不起作用。