在Javascript中显示数量

时间:2013-03-31 15:54:44

标签: javascript

当我点击我的按钮时,我正试图在JavaScript中显示价格,但它只是向我显示我的警报。谁能告诉我哪里出错了?这是我的功能:

function prompttotalCost() {
    var totalCost;
    var costPerCD;
    var numCDs;
    numCDS = prompt("Enter the number of Melanie's CDs you want to buy");
    if (numCDS > 0) {
        totalCost = totalCost + (costPerCD * numCDs);
        alert("totalCost+(costPerCD*numCDs)");
        totalCost = 0;
        costPerCD = 5;
        numCDs = 0;
    } else {
        alert("0 is NOT a valid purchase quantity. Please press 'OK' and try again");
    } // end if
} // end function prompttotalCost

1 个答案:

答案 0 :(得分:1)

问题是numCDs是一个字符串,而不是一个数字,因为prompt返回一个字符串。你可以,例如使用parseInt将其转换为数字:

numCDS = parseInt(prompt("Enter the number of Melanie's CDs you want to buy"));

接下来的事情:在使用它之前,你没有给totalCost赋值 - 这很糟糕。将var totalCost;更改为var totalCost = 0;或将totalCost = totalCost + (costPerCD * numCDs);更改为totalCost = (costPerCD * numCDs);

此外,在alert调用中,您要将要执行的内容作为代码放入字符串中。变化

alert("totalCost+(costPerCD*numCDs)");

这样的事情:

alert("totalCost is "+totalCost);