所得税计算器的未定义输出。 JavaScript

Question

this is an exercise from Murach's Javascript and Jquery book.这是 Murach 的 Javascript 和 Jquery 书中的一个练习。 An income tax calculator.所得税计算器。 The code is pretty self explanatory.代码是不言自明的。 The error: undefined is popping up where the value of the tax owed should be.错误：undefined 出现在应缴税款的位置。 commented out if statement outputted the same 'undefined' error.注释掉 if 语句输出相同的“未定义”错误。 The documentation said, undefined usually is outputted when a variable isn't assigned or returned and i've done all that.文档说，未定义通常在未分配或返回变量时输出，而我已经完成了所有这些。

JS JS

"use strict";
var $ = function (id) {
    return document.getElementById(id);
};

   var income;
   var taxOwed;
   var calculateTax = function(income){
    /*if (income > 0 && income < 9275){
        //incomeTax = taxableIncome - 0;
        //percentIT = incomeTax * (10/100);
        taxOwed = (income - 0) * (10/100) + 0;
        taxOwed = parseFloat(taxOwed);
        taxOwed = taxOwed.toFixed(2); //the tax should be rounded two 
        return taxOwed;
    }*/

    if (income < 9275){
        taxOwed = income - 0 * .10 + 0;
    }else if(income > 9275){
        taxOwed = ((income - 9275) * .15) + 927.50;
    }
    return taxOwed;

};

var processEntry = function(){
    income = parseInt($("income").value); //users entry should be converted 
    if(isNaN(income)){
        alert("Entry must be a number");
    }else if (income <= 0){
        alert("income must be greater than 0");
    }else{
        $("taxOwed").value = calculateTax(income);
    }
};  

window.onload = function () {
    $("calculate").onclick = processEntry;
    $("income").focus();
};

HTML HTML

<!DOCTYPE html>
<html>
<head>
    <meta charset="utf-8">
    <title>Ace</title>
    <link rel="stylesheet" href="styles.css">
</head>

<body>
    <h1>Income Tax Calculator</h1>

    <label>Enter taxable income:</label>
    <input type="text" id="income" /> <!--income is variable name for taxable income-->
    <input type="button" value="Calculate" name="calculate" id="calculate" /><br><br>

    <label>Income tax owed:</label>
    <input type="text" id="taxOwed"><br> <!--tax is variable name for taxOwed*-->
<script src="calculate_tax.js"></script>
</body>
</html>

Answer 1

You probably aren't passing anything in. put a debugger statement after income and open your dev console, check if the variable actually has a value.您可能没有传入任何内容。在收入之后放置一个调试器语句并打开您的开发控制台，检查该变量是否确实具有值。

//use val() not value
income = parseInt($("income").val());
debugger;

所得税计算器的未定义输出。 JavaScript

问题描述

1 个解决方案

解决方案1
1 2018-02-09 22:10:43

所得税计算器的未定义输出。 JavaScript

问题描述

1 个解决方案

解决方案1 1 2018-02-09 22:10:43

解决方案1
1 2018-02-09 22:10:43