尝试在JavaScript中计算简单的折扣和营业税
[英]Trying to calculate a simple discount and sales tax in javascript
问题描述
I'm just trying to input an number and then add 10% and then take that total and .08% tax. 
我只是想输入一个数字，然后加10％，然后取总计和0.08％的税。 Can you please help me figure out what I'm doing wrong. 您能帮我弄清楚我在做什么错。 I sure it is something simple I'm overlooking but I'm new to this and can't figure what is wrong. 我确定这是我所忽略的简单事情，但是我对此并不陌生，无法弄清楚出什么问题了。
<!doctype html> <html lang="en"> <head> <meta charset="utf-8"> <title>Price tool</title> </head> <body> <form name="operation_form"> <label style="font-size:20px"><b>Price Tool</b></label> <br/> <br/> <br/> <label>Item Price: </label><input type="number" name='acertscore' value="" /> <br/> <br/> <label><b>Total is:</b></label><input type="number" name="answerbox"> <br/> <input type="button" value="Calculate" onclick="costCalc();" /> <br/> <input type="button" value="Reset" onClick="this.form.reset()" /> </form> <script type="text/javascript"> function costCalc() { var form = document.forms["operation_form"]; var x = form["acertscore"].value; var cost = (x * .1) + x; var answer = (cost * .08) + cost; form["answerbox"].value = answer; } </script> </body> </html>
3 个解决方案
解决方案1
2 2018-01-31 22:56:49
I logged the value of 'cost' in your code when I start with the value 100 当我从值100开始时，我在您的代码中记录了“费用”的值
var cost = (x * .1) + x;
console.log(cost);
and got a value of '10100' 的值为“ 10100”
But if I make sure that x is a number I get the correct value (110) 但是，如果我确定x是一个数字，我会得到正确的值（110）
var cost = (x * .1) + Number(x);
console.log(cost);
And I get 118.8 for the total. 我总共得到118.8。
解决方案2
1 已采纳 2018-01-31 22:48:58
When you retrieve the value from your input control, it comes through as a string value. 从输入控件中检索值时，它作为字符串值出现。
var x = form["acertscore"].value; // x is a string
If you convert this to a number immediately you'll avoid additional problems. 如果立即将其转换为数字，将避免其他问题。
var x = Number(form["acertscore"].value); // x is a number
function costCalc() { var form = document.forms["operation_form"]; var x = Number(form["acertscore"].value); var cost = (x * .1) + x; var answer = (cost * .08) + cost; form["answerbox"].value = answer; }
<form name="operation_form"> <label style="font-size:20px"><b>Price Tool</b></label> <br/> <br/> <br/> <label>Item Price: </label><input type="number" name="acertscore" value="" /> <br/> <br/> <label><b>Total is:</b></label><input type="number" name="answerbox"> <br/> <input type="button" value="Calculate" onclick="costCalc();" /> <br/> <input type="button" value="Reset" onClick="this.form.reset()" /> </form>
解决方案3
-1 2018-01-31 22:39:57
The problem is that your answer number is so long that it tries to display exponents. 问题在于您的answer号太长，以至于无法显示指数。 Because of this, the number gets treated as a string, though you've specified that the output goes into an <input> field with a type of number . 因此，尽管已将输出指定为number type的<input>字段，但该数字仍被视为字符串。 Because your answer is not a number, it can't be displayed. 由于您的answer不是数字，因此无法显示。
To resolve this, you can parse the output as a float before displaying it: 要解决此问题，您可以在显示输出之前将其解析为float ：
form["answerbox"].value = parseFloat(answer);
function costCalc() { var form = document.forms["operation_form"]; var x = form["acertscore"].value; var cost = (x * .1) + x; var answer = (cost * .08) + cost; form["answerbox"].value = parseFloat(answer); }
<form name="operation_form"> <label style="font-size:20px"><b>Price Tool</b></label> <br/> <br/> <br/> <label>Item Price: </label><input type="number" name='acertscore' value="" /> <br/> <br/> <label><b>Total is:</b></label><input type="number" name="answerbox"> <br/> <input type="button" value="Calculate" onclick="costCalc();" /> <br/> <input type="button" value="Reset" onClick="this.form.reset()" /> </form>
Hope this helps! 希望这可以帮助！
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