Question

所以我用html和javascript创建了这个简单的网站，用户输入他们的零钱并将其全部转换为最终的金额。由于一些非常奇怪的原因，当镍和硬币是一定数量时，会添加大量小数位，例如当镍是8时。即使这些小数位不是那样，总量也有很长的小数位。由于所有计算都不应超过2位小数，因此我有点难过。对于我将在代码中看到的解决方案，我只是将数字四舍五入，因为这个页面用于编程课程而不是数学课程，我认为这对于作业来说并不重要，但我很好奇为什么这样做正在发生的事情，如果我将来创造一些严肃的东西，我可以避免这种类型的问题。

您可以在此处查看此代码，http://192.236.14.50/part4/

单击Change Converter并输入值并点击转换。如果你打开了javascript控制台，你会看到我在说什么。以下是javascript代码。

function registerList3() {
    img = document.getElementById("moneyButton");
    img.addEventListener("click",   function() { calculateMoney(); }, false);

}

// Function calculateMoney tallies up all the change inputs and calculates the total

function calculateMoney() {

    // Create the various var's for each input and assign to their values.
    var pennies = document.getElementById("pennies").value;
    var nickels = document.getElementById("nickels").value;
    var dimes = document.getElementById("dimes").value;
    var quarters = document.getElementById("quarters").value;
    var loonies = document.getElementById("loonies").value;
    var toonies = document.getElementById("toonies").value;
    console.log("Pennies " + pennies);
    console.log("Nickels " + nickels);
    console.log("Dimes " + dimes);
    console.log("Quarters " + quarters);
    console.log("Loonies " + loonies);
    console.log("Toonies " + toonies);

    // Multiply pennies amount by 0.01.
    var penniesAmount = parseFloat(pennies * 0.01);
    // Multiple nickels amount by 0.05.
    var nickelsAmount = parseFloat(nickels * 0.05);
    // Multiple dimes amount by 0.1.
    var dimesAmount = parseFloat(dimes * 0.1);
    // Multiple quarters amount by 0.25.
    var quartersAmount = parseFloat(quarters * 0.25);
    // Loonies amount equals itself, no multiplication needed.
    var looniesAmount = parseFloat(loonies);
    // Multiple toonies amount by 2.
    var tooniesAmount = parseFloat(toonies * 2);

    console.log("-----AMOUNTS-----");
    console.log("Pennies " + penniesAmount);
    console.log("Nickels " + nickelsAmount);
    console.log("Dimes " + dimesAmount);
    console.log("Quarters " + quartersAmount);
    console.log("Loonies " + looniesAmount);
    console.log("Toonies " + tooniesAmount);

    // Create totalAmount var, equal to all amounts added together.
    var totalAmount = penniesAmount + nickelsAmount + 
        dimesAmount + quartersAmount +  looniesAmount + tooniesAmount;
    console.log("Total Amount " + totalAmount);

    // If the total amount is not a number (NaN)...
    if (isNaN(totalAmount)) {
        // Change total label to 0.
        document.getElementById("totalMoney").innerHTML = 0;
        // Alert user to input only numbers.
        alert("Please enter numbers only");
    }
    // Else if total amount is a number...
    else {
        // Create rounded amount and round total amount to 2 decimal places.
        // Shouldn't be neccessary, but it is. See notes above.
        var roundedAmount = Math.round(totalAmount * 100) / 100;
        // Change total money label to rounded amount.
        document.getElementById("totalMoney").innerHTML = roundedAmount;
    }

}

所以再一次，这个问题并不是关于如何围绕它，因为我已经这样做了，但是为什么它首先要做到这一点。我从未在任何其他语言中体验过这一点。

简单的Javascript计算结束了巨大的小数位

0 个答案: