最佳jquery计算器实现和实现验证

Question

嘿，伙计们，这是我有史以来的第一个jquery脚本，我想知道你们是否看到了任何错误或坏习惯，无论是在我的代码符号中还是在一般情况下，我都应该尽早发布。。请注意，在我暗示验证后，它将在someones网站上成为真实的东西。此外，你建议我如何实施验证示例，请

<script type="text/javascript" src="jquery.js">
</script>
<script type="text/javascript">
$(document).ready(function(e) {
$(".calculatebutton").on("click",function()
{
//perform a input type check when i learn rregex
var item_cost=$("#itemCost").val();
if($(this).val()=="Cash Payment")
{
    var answer=item_cost*0.10;
}
else
{
    var answer=item_cost*0.12;
}
answer+=parseInt(item_cost);
$("#total").val(answer);
 })
});
</script>

Answer 1

一个带有注释的小示例

http://jsfiddle.net/blackjim/JktYg/2/

$(document).ready(function (e) {
    $(".calculatebutton").on("click", function () {
        //perform a input type check when i learn rregex
        var answer = 0,
            item_cost = $("#itemCost").val(); // this is a string, NOT a number
        // check if you got a number, with your way or criteria
        if(isNaN(item_cost) || item_cost === true || item_cost === ''){  
            $("#total").val("Not a Number here");
            return false; // you didn't
        }
        item_cost = parseFloat(item_cost); // or use parseInt if you want integer
        if ($('.calculatebutton').text() === 'Cash Payment'){ // use always === for equality
            answer = item_cost * 0.10;
        } else {
            answer = item_cost * 0.12;
        }
        answer += item_cost;
        $("#total").val(answer);
    })
});