Question

它甚至都没有运行。 do while循环有问题。我假设它是所有if语句的东西？如果有人可以帮助我，我会非常感激。感谢。

        do {
        entry = prompt("Enter taxable income as a valid number\n" +
                       "Or enter 99999 to end entries", 99999);
        entry = parseInt(entry);

        // calculate the tax owed here
        if (entry < 0){
            document.write("Please enter a positive number");
        }
        if (entry > 0 && entry < 8701){
            tax_owed = entry * 0.10;
        }
        if (entry > 8700 && entry < 35351){
            tax_owed = 870 * 0.15;
            tax_owed += entry;
        }
        if (entry > 35350 && entry < 85651){
            tax_owed = 4867 * 0.25;
            tax_owed += entry;
        }
        if (entry > 85650 && < 178651){
            tax_owed = 17442 * 0.28;
            tax_owed += entry;
        }
        if (entry > 178650 && entry < 388351){
            tax_owed = 43482 * 0.33;
            tax_owed += entry;
        }
        if (entry > 388350){
            tax_owed = 112683 * 0.35;
            tax_owed += entry;
        }

        alert("Tax owed is " + tax_owed);
    }
    while (entry != 99999);

Answer 1

在你的21行

if (entry > 85650 && < 178651){ // there is no operand between && and <.

我认为应该是

if (entry > 85650 && entry< 178651){

Answer 2

在if (entry > 85650 && < 178651)行上如果仔细观察，会发现您没有将第二个数字与任何数字进行比较。它应该是if (entry > 85650 && entry < 178651)

Answer 3

已找到< 178651之前缺少操作数的错误，但如果您希望代码具有较少的潜在错误，我建议进行轻量级重构。

使用else if会更有效率。一旦找到对应于给定entry值的块，程序将停止检查其他条件。此外，您只需指定区分范围的值（您的＆＃34;里程碑＆＃34;），而不是像entry < 8701后跟entry > 8700那样重复它们。最后，当您输入99999时，它将修复正在打印tax_owed = ..something like 140000..的其他错误。
更改循环的条件（引入布尔变量）将更具可读性。
我根本不是税务人员，但您确定要添加tax_owed += entry;吗？我的意思是，当我宣布10000美元时，我真的欠10130.5美元吗？在任何情况下，拥有1行而不是2行更具可读性：tax_owed = entry + 17442 * 0.28; // but do you really add 'entry'?。

所以，代码将是这样的：

continueEntering = true;

while ( continueEntering ) {
    tax_owed = 0;
    entry = prompt("Enter taxable income as a valid number\n" + "Or enter 99999 to end entries", 99999);
        entry = parseInt(entry);

    if (entry == 99999) {
        continueEntering = false;
    } else if (entry < 0){
        alert("Please enter a positive number"); 
    } else if (entry <= 8700){
        tax_owed = entry * 0.10;
    } else if (entry <= 35350){
        tax_owed = 870 * 0.15 + entry;
    } else if (entry <= 85650){
        tax_owed = 4867 * 0.25 + entry;
    } else if (entry <= 178650){
        tax_owed = 17442 * 0.28 + entry;
    } else if (entry <= 388350){
        tax_owed = 43482 * 0.33 + entry;
    } else {
        tax_owed = 112683 * 0.35 + entry;
    }

    alert("Tax owed is " + tax_owed);
}

如评论中所述，最好不要在循环体内使用值本身。如果这些值存储在变量中，那么更容易将这些值更改为一天。在这里你可以使用2个数组。你可以打电话给他们，比如thresholds[]和tax_percentage[]，或者其他什么（你比我知道的更好）。使用数组的好处是，您可以通过原始if循环中的一个for循环替换while语句的序列。

================更新====================

以下是重构上述代码以使用for循环代替大量if的方法。

continueEntering = true;

while ( continueEntering ) {
    tax_owed = 0;
    exitValue = 99999;

    tax_threshold = [ 0, 8700, 35350, 85650, 178650, 388350 ];
    tax_rate = [ 0.10, 0.15, 0.25, 0.28, 0.33, 0.35 ];
    additional_tax = [ 0, 870, 4867, 17442, 43482, 112683 ];

    entry = prompt("Enter taxable income as a valid number\n" + 
        "Or enter " + exitValue + " to end entries", exitValue);
    entry = parseInt(entry);

    if (entry == exitValue) {
        continueEntering = false;
    } else if (entry < 0){
        alert("Please enter a positive number"); 
    } else {

        for( i = tax_threshold.length-1; i >= 0; i-- ) {
            if ( entry > tax_threshold[i] ) {
                tax_owed = entry - tax_threshold[i];
                tax_owed *= tax_rate[i];
                tax_owed += additional_tax[i];
                break;
            }
        }
    }

    alert("Tax owed is " + tax_owed.toFixed(2));
}

Answer 4

好的，我想出了计算税收的方法。你们是对的。我离开了。我正在使用2012年的所得税政策，因为这是我的教授希望我们使用的。再次感谢大家的帮助。我真的很喜欢这个网站！非常适合我们n00bs。

    var tax_owed = 0;
    var entry;

    continueEntering = true;

    while (continueEntering) {
        tax_owed = 0;
        entry = prompt("Enter taxable income as a valid number\n" + "Or enter 99999 to end entries", 99999);
        entry = parseInt(entry);

        if (entry == 99999) {
            continueEntering = false;
        } else if (entry < 0){
            alert("Please enter a positive number"); 
        } else if (entry <= 8700){
            tax_owed = entry * 0.10;
        } else if (entry <= 35350){
            tax_owed = entry - 8700;
            tax_owed *= 0.15;
            tax_owed += 870;
        } else if (entry <= 85650){
            tax_owed = entry - 35350;
            tax_owed *= 0.25;
            tax_owed += 4867;
        } else if (entry <= 178650){
            tax_owed = entry - 85650;
            tax_owed *= 0.28;
            tax_owed += 17442;
        } else if (entry <= 388350){
            tax_owed = entry - 178650;
            tax_owed *= 0.33;
            tax_owed += 43482;
        } else if (entry > 388350){
            tax_owed = entry - 388350;
            tax_owed *= 0.35;
            tax_owed += 112683;
        }

        alert("Tax owed is " + tax_owed.toFixed(2));

}

找不到此javascript代码中的错误

4 个答案: