我想構建一個簡單的預算計算器,每次我點擊我的提交按鈕,我什麼也沒有發生。當我嘗試在控制檯中檢查我的變量值時,即使在我的輸入框中鍵入了值之後,它們仍顯示爲空。誰能告訴我我做錯了什麼?在查看其他問題後,我一直無法找到與我的問題相關的答案。JavaScript getElementById總是返回null
<!DOCTYPE html>
<html>
<head>
<title>Budget Calculator</title>
<style>
input {display:block;}
#clear {float:left;}
#submit {float:left;}
</style>
<script type="text/javascript">
var kms = document.getElementById("kmTravelled");
var rent = document.getElementById("rentPerMonth");
var carCost = document.getElementById("carPayment");
var costPerTrip = (kms/12.75)*20;
var total = Math.round((costPerTrip + rent + carCost)*100)/100;
function calculate()
{
document.getElementById("calculator").innerHTML = total;
}
</script>
</head>
<body>
<form id="myForm")>
Km travelled per day: <input type="number" name="kmTravelled" />
Rent per month: <input type="number" name="rentPerMonth" />
Car payment per month: <input type="number" name="carPayment" />
</form>
<button id="submit" type="button" onclick="calculate();">
Submit
</button>
<button id="clear" type="clear">
Clear
</button>
<p id = "calculator">
</p>
<script>
calculate();
</script>
</body>
只是一個小提示:'