如何使此IF语句发挥作用

How to make this IF statement work

本文关键字：作用 语句 何使此 IF      更新时间：2023-10-20

好吧，我正在尝试运行代码，让人们输入一笔钱，然后它显示他们每天赚多少钱的估计值。如果文本框中没有数字，我希望它弹出一个ERROR。我应该怎么做？

这是我当前的代码：

<!DOCTYPE html>
<html>
<head>
    <title> MoneyPerYear </title>
    <link type="text/css" rel="stylesheet" href="money.css">
</head>
<body>
    <p id="header"> Enter yearly income to estimate daily earnings </p>
    <input type="text" id="textmoney">
    <div onclick="moneyFunction()" id="moneydiv"> <p id="divtext">Calculate</p> </div>
    <p id="demo"></p>

    <script>
    function moneyFunction() {
        var money = document.getElementById('textmoney').value;
        var dailyE = money/365;
        document.getElementById('demo').innerHTML = (dailyE);
    }
    if ( document.getElementById('textmoney').value; == 0) {
        document.getElementById('demo').innerHTML = "ERROR";
    }
    </script>
</body>
</html>

所有内容如下：

 <!DOCTYPE html>
    <html>
    <head>
        <title> MoneyPerYear </title>
        <link type="text/css" rel="stylesheet" href="money.css">
    </head>
   <body>
    <p id="header"> Enter yearly income to estimate daily earnings </p>
    <input type="text" id="textmoney">
    <button onclick="moneyFunction()" id="moneydiv"> <p id="divtext">Calculate</p> </button>
    <p id="demo"></p>

    <script>
    function moneyFunction() {
        var money = document.getElementById('textmoney').value;
            if ( document.getElementById('textmoney').value == 0) {
              alert("Error");
    }
        var dailyE = money/365;
        document.getElementById('demo').innerHTML = (dailyE);
    }

    </script>
</body>
    </html>


function moneyFunction() {
    var money = +(document.getElementById('textmoney').value) || 0; //parse required
    var dailyE = money / 365;
    //var result = money === 0 ? 'ERROR' : dailyE;
    var result = money === 0 ? 'ERROR' : parseFloat(dailyE).toFixed(3); //round-off
    document.getElementById('demo').innerHTML = result;
  } //closing bracket
#moneydiv {
  border: 1px solid grey;
  padding: 5px;
  background: skyblue;
  display: inline-block;
  cursor: pointer;
}
<p id="header">Enter yearly income to estimate daily earnings</p>
<input type="text" id="textmoney">
<div onclick="moneyFunction()" id="moneydiv">
  <p id="divtext">Calculate</p>
</div>
<p id="demo"></p>

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