用户输入的时间为零，即使它在javascript中应该更多

我正在计算用户从开始打字到停止打字的时间。我把两个变量放在起点和终点，然后把它们相互减去。但它总是返回零。如果可能的话，你能给出一个简单的方法来计算wpm吗？最后，我想在用户正确键入10个单词时计算每分钟的单词数。所以我需要从他们开始到完成提示的时间

谢谢

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 () {
  var value = element.value;

   if (value.includes("m")) {
     var start = Date.now();
  } 

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

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

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

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

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

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

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

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

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

  if (value.includes("man become as and through find would here and before")) {
    document.getElementById('word-10').style.backgroundColor = 'green';
  } else {
    document.getElementById('word-10').style.backgroundColor = "red";
  }

   if (value.includes("man become as and through find would here and before")) {
     var end = Date.now();
 
  }
  let millis = end-start;

  console.log(millis)

  
}

HTML:

答复
人变成
通过这里和之前找到的
进入
```

首先，

value.includes（“m”）

每次都是真的，因此每次启动函数时计时器都会重新启动。相反，请使用

value==“m”

：

您需要在

if

语句外部声明

var end

和

var start

，并在内部设置它：

var start;
if (value === "m") {
  start = Date.now();
}
// other code...
var end;
if (value.includes("man become as and through find would here and before")) {
  end = Date.now();
}
let millis = end-start;

---

另外，我建议在

end

和

start

之间留出一个空格

end start

可以是一个变量名。

你是说

=

而不是

includes

？它只给出零。你需要对

start

执行同样的操作。我将编辑它，它仍然给出NaN，然后是0。@IrfanS而不是

值。包括（“m”）

，它应该是

值==“m”

。我将再次编辑againSorry，因为它会打扰您，但现在只有在我编辑console.log（millis）时才会给出NaN作为答案

if (value === "m") {
  start = Date.now();
}

var start;
if (value === "m") {
  start = Date.now();
}
// other code...
var end;
if (value.includes("man become as and through find would here and before")) {
  end = Date.now();
}
let millis = end-start;