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javascript - JavaScript中的除法给出未定义的错误

问题描述

我试图计算用户开始输入到结束之间的时间。Date.now();所以我用这个函数命名了两个常量。每当我运行程序时，它总是给出错误：ReferenceError: start is not defined at HTMLInputElement.element.onkeyup (/main.js:86:16)代码如下：

Javascript：

var input = document.getElementById("boch");
input.addEventListener("keyup", function (event) {
  if (event.keyCode === 13) {
    event.preventDefault();
    document.getElementById("bocho").click();
  }
});


var element = document.querySelector("#boch");

element.onkeyup = function () {
  变量值 = 元素值；

   if (value.includes("m")) {
     让开始 = Date.now();
  }

  if (value.includes("man")) {
    document.getElementById('word-1').style.backgroundColor = 'green';
  } 别的 {
    document.getElementById('word-1').style.backgroundColor = "red";
  }

  if (value.includes("man become")) {
    document.getElementById('word-2').style.backgroundColor = 'green';
  } 别的 {
    document.getElementById('word-2').style.backgroundColor = "red";
  }

  if (value.includes("man become as")) {
    document.getElementById('word-3').style.backgroundColor = 'green';
  } 别的 {
    document.getElementById('word-3').style.backgroundColor = "red";
  }

  if (value.includes("man become as and")) {
    document.getElementById('word-4').style.backgroundColor = 'green';
  } 别的 {
    document.getElementById('word-4').style.backgroundColor = "red";
  }

  if (value.includes("man become as and through")) {
    document.getElementById('word-5').style.backgroundColor = 'green';
  } 别的 {
    document.getElementById('word-5').style.backgroundColor = "red";
  }

  if (value.includes("man become as and through find")) {
    document.getElementById('word-6').style.backgroundColor = 'green';
  } 别的 {
    document.getElementById('word-6').style.backgroundColor = "red";
  }

  if (value.includes("man become as and through find would")) {
    document.getElementById('word-7').style.backgroundColor = 'green';
  } 别的 {
    document.getElementById('word-7').style.backgroundColor = "red";
  }

  if (value.includes("man become as and through find will here")) {
    document.getElementById('word-8').style.backgroundColor = 'green';
  } 别的 {
    document.getElementById('word-8').style.backgroundColor = "red";
  }

  if (value.includes("man become as and through find will here and")) {
    document.getElementById('word-9').style.backgroundColor = 'green';
  } 别的 {
    document.getElementById('word-9').style.backgroundColor = "red";
  }

  if (value.includes("man 通过 find will here 和 before")) {
    document.getElementById('word-10').style.backgroundColor = 'green';
  } 别的 {
    document.getElementById('word-10').style.backgroundColor = "red";
  }

   if (value.includes("man 通过 find will here 和 before")) {
     让结束 = Date.now();
 
  }
  让millis =开始/结束；

  console.log(`经过的秒数 = ${Math.floor(millis / 1000)}`);


}

html:

<html>

<head>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width">
    <title>repl.it</title>
    <link href="style.css" rel="stylesheet" type="text/css" />
</head>
<h1>
   <span id="word-1">man</span> <span id="word-2">become</span> <span id="word-3">as</span>
   <span id="word-4">and</span> <span id="word-5">through</span> <span id="word-6">find</span> <span id="word-7">would</span> <span id="word-8">here</span> <span id="word-9">and</span> <span id="word-10">before</span>
</h1>

<input type="text" id="boch" autocomplete="off">

        </div>
        <div id="typing-area">

      <button id="bocho" onclick="document.getElementById('boch').value = ''">Enter</button>

</html>




<script src="main.js"></script>

标签： javascripthtmlcssdate

解决方案

您声明变量“start”的位置与使用时不同。这意味着

let millis = start/end;

看不到开始。

您需要将 let 更改为 var。这样范围就不会以同样的方式受到限制

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