javascript - 在 for 循环中使用 <label> &lt;input&gt; <br>

Question

请问如何在for循环中添加标签、输入和br。我正在尝试创建一个应用程序来使用 for 循环计算分数/GPA。基本上，如果我输入 4，那么将显示 4 个测试分数框供我输入(默认值为 150)- 我最多可以输入 5。

我在将 label、input 和 br 放入 for 循环时遇到了问题 - 代码没有问题并且可以运行，但您显然看到我没有使用 label、input 和 br 标签。 请问如何添加这些？

例如，如果我在考试次数中输入 3，那么 setupInputBox() 将生成三个标签、三个输入和三个 br 元素。

我在下面附上了我的代码。

非常感谢!

// define a function so that in js code, $ can be used to replace document.getElementById
var $ = function(id) {
  return document.getElementById(id);
};

var numInputs = 1; //default setting, showing one test score input box

//define setupInputBox function to add more test score inputs boxes 
var setupInputBox = function() {

  $('testInputs').innerHTML = "";
  $('scoreTotal').value = "";
  $('scoreAvg').value = "";
  $('scoreFinal').value = "";

  numInputs = $('numscores').value;
  numInputs = parseInt(numInputs);
  // convert inputs into integer numerical value
  //step-1.1: Add a condition in if() statement
  //if user input for number of test scores is valid and in the range 1 to 5
  if (Number.isInteger(numInputs) && numInputs >= 1 && numInputs <= 5) {
    var mainDiv = document.getElementById("testInputs");
    for (var i = 0; i < numInputs; i++) {
      //Step-1.2.1: create new <label>, <input>, and <br> elements (use createElement() method)
      var lbl = document.createElement('label');
      var inp = document.createElement("input");
      var br = document.createElement("br");

      //Step-1.2.2: create text content node for each new <label> element  ( use createTextNode() method )
      lbl.append(document.createTextNode("Test-" + (i + 1)));

      //Step-1.3.1: add for attribute to each new <label> element  ( use setAttribute() method)
      lbl.setAttribute("for", "score" + (i + 1));

      //Step-1.3.2: add id, type, and value attributes to new <input> elements ( use setAttribute() method)
      inp.setAttribute("id", "score" + (i + 1));
      inp.setAttribute("value", "150");
      inp.setAttribute("type", "number");

      //Step-1.4: append each new <label>, <input>, and <br> elements to the <div> element with id=”testInputs”.
      mainDiv.append(lbl, inp, br);

    }
  }
};
//whenever user changes selection on number of test scores to consider, setupInputBox function will be executed again
$('numscores').oninput = setupInputBox;

//define processEntries function to get user inputted test scores, do input validation, and caculate total and average points and 
//determine the final letter grade.  Display all results on web page.
var processEntries = function() {
  $('scoreTotal').value = "";
  $('scoreAvg').value = "";
  $('scoreFinal').value = "";

  var score = []; //define an array to hold test scores

  var message = ""; //define a variable for containing and displaying error message

  var totalscore = 0,
    avgScore, finalScore;

  var isValid = true;

  for (var i = 0; i < numInputs; i++) //
  {
    $("score" + (i + 1)).className = "";

    //step 2.1: add js code to read in each user inputted test score(s) from input test score boxes on the web page.
    var test = document.getElementById("score" + (i + 1));
    var testScore = parseFloat(test.value);

    //step 2.2: add js code to validate each test score to make sure all inputted test scores are numerical values
    //between 0 and 150 (i.e., no less than 0 and no greater than 150 points).
    if (!Number.isNaN(testScore) && testScore >= 0 && testScore <= 150) {
      //if a test score is valid, add that test score to the score array.
      score.push(testScore);
    } else {
      isValid = false;
      //if a test score is invalid, generate error message, and add that error messge to message string.
      message += "Test-" + (i + 1) + " score input is invalid. Should be a number between 0 and 150.\n"
      test.setAttribute("class", "error");
    }

  }
  console.log(score); //print out score array in console
  console.log(message); //print out message string in console


  if (isValid) {
    //step2.3: add js so that when all inputted test scores are valid, compute total points, average points (with zero decimal place), and
    //final letter grade, and display them in the input boxes in the <div> element with id=’result’ on the web page.
    for (var j = 0; j < numInputs; j++) {
      totalscore += score[j];
    }

    totalscore = totalscore.toFixed(1);

    avgScore = totalscore / numInputs;
    avgScore = avgScore.toFixed(1);

    var scoreTotal = document.getElementById('scoreTotal');
    scoreTotal.value = totalscore.toString();

    var scoreAvg = document.getElementById('scoreAvg');
    scoreAvg.value = avgScore.toString();

    avgScore = parseFloat(avgScore);

    if (avgScore <= 150 && avgScore >= 120)
      finalScore = "A";
    else if (avgScore < 120 && avgScore >= 100)
      finalScore = "B";
    else if (avgScore < 100 && avgScore >= 80)
      finalScore = "C";
    else if (avgScore < 80 && avgScore >= 60)
      finalScore = "D";
    else if (avgScore < 60)
      finalScore = "F";

    var scoreFinal = document.getElementById("scoreFinal")
    scoreFinal.value = finalScore
  } else {
    //If not all inputted test scores are valid, then create an alert box to display an error message
    alert(message);
  }
}; //end of processEntries function

//each time when calculate button is clicked, inputted test scores will be evaluated and 
$("calculate").onclick = function() {
  if (numInputs > 0 && numInputs < 6)
    processEntries();
};
$("numscores").focus();

@import url(http://fonts.googleapis.com/css?family=Wellfleet);
body {
  font-family: 'Wellfleet', Arial, Helvetica, sans-serif;
  background-color: white;
  margin: 0 auto;
  width: 60%;
  min-width: 600px;
  border: 3px solid blue;
  padding: 0 1em .5em;
}

h1 {
  color: blue;
  margin: .5em 0;
}

#teacher {
  float: right;
  margin: 0px 30px 0px 0px;
}

label {
  float: left;
  width: 10em;
  text-align: right;
  margin-bottom: .5em;
}

input {
  width: 5em;
  margin-left: 1em;
  margin-bottom: .5em;
}

input.error {
  background-color: yellow;
}

#s1 {
  display: inline-block;
}

#s1 input {
  vertical-align: center;
  float: left;
}

<!DOCTYPE html>
<html>

<head>
  <meta charset="UTF-8">
  <title>Test Score App</title>
  <link rel="stylesheet" href="score.css">
</head>

<body>
  <main>
    <h2>The Test Scores App</h2>
    <img src="teacher.png" id="teacher" alt="teacher" width="177" height="277">

    <div id="s1">
      <label for="numscores">How many tests you want to consider?</label>
      <input type='number' id='numscores' min='1' max='10' value='1'>
    </div>

    <div id="testInputs">
      <label for="score1">Test-1:</label>
      <input type='number' id='score1' value='150' /><br>
    </div>

    <div id='result'>
      <label for="scoreTotal">Total Points:</label>
      <input type="number" id="scoreTotal" disabled><br>

      <label for="scoreAvg">Avg Grade:</label>
      <input type="number" id="scoreAvg" disabled><br>

      <label for="scoreFinal">Final Letter Grade:</label>
      <input type="text" id="scoreFinal" disabled><br>

      <label>&nbsp;</label>
      <input type="button" id="calculate" value="Calculate">
    </div>

  </main>
  <script src="testScoreV2.js">
  </script>
</body>

</html>

Answer 1

使用 template literal你可以让这变得更简单

// define a function so that in js code, $ can be used to replace document.getElementById
var $ = function(id) {
  return document.getElementById(id);
};

var numInputs = 1; //default setting, showing one test score input box

//define setupInputBox function to add more test score inputs boxes 
var setupInputBox = function() {

  $('testInputs').innerHTML = "";
  $('scoreTotal').value = "";
  $('scoreAvg').value = "";
  $('scoreFinal').value = "";
  //string to hold our new html
  let newHTML = "";

  numInputs = $('numscores').value;
  numInputs = parseInt(numInputs);
  // convert inputs into integer numerical value
  //step-1.1: Add a condition in if() statement
  //if user input for number of test scores is valid and in the range 1 to 5
  if (Number.isInteger(numInputs) && numInputs >= 1 && numInputs <= 5) {
    var mainDiv = document.getElementById("testInputs");
    for (var i = 0; i < numInputs; i++) {
      //Create new html using template literal
      newHTML += `<label for='score${i+1}'>Test - ${i+1}</label><input type='number' value='150' id='score${i+1}'><br>`;
    }
    //Update the div
    mainDiv.innerHTML += newHTML;
  }
};
//whenever user changes selection on number of test scores to consider, setupInputBox function will be executed again
$('numscores').oninput = setupInputBox;

//define processEntries function to get user inputted test scores, do input validation, and caculate total and average points and 
//determine the final letter grade.  Display all results on web page.
var processEntries = function() {
  $('scoreTotal').value = "";
  $('scoreAvg').value = "";
  $('scoreFinal').value = "";

  var score = []; //define an array to hold test scores

  var message = ""; //define a variable for containing and displaying error message

  var totalscore = 0,
    avgScore, finalScore;

  var isValid = true;

  for (var i = 0; i < numInputs; i++) //
  {
    $("score" + (i + 1)).className = "";

    //step 2.1: add js code to read in each user inputted test score(s) from input test score boxes on the web page.
    var test = document.getElementById("score" + (i + 1));
    var testScore = parseFloat(test.value);

    //step 2.2: add js code to validate each test score to make sure all inputted test scores are numerical values
    //between 0 and 150 (i.e., no less than 0 and no greater than 150 points).
    if (!Number.isNaN(testScore) && testScore >= 0 && testScore <= 150) {
      //if a test score is valid, add that test score to the score array.
      score.push(testScore);
    } else {
      isValid = false;
      //if a test score is invalid, generate error message, and add that error messge to message string.
      message += "Test-" + (i + 1) + " score input is invalid. Should be a number between 0 and 150.\n"
      test.setAttribute("class", "error");
    }

  }
  console.log(score); //print out score array in console
  console.log(message); //print out message string in console


  if (isValid) {
    //step2.3: add js so that when all inputted test scores are valid, compute total points, average points (with zero decimal place), and
    //final letter grade, and display them in the input boxes in the <div> element with id=’result’ on the web page.
    for (var j = 0; j < numInputs; j++) {
      totalscore += score[j];
    }

    totalscore = totalscore.toFixed(1);

    avgScore = totalscore / numInputs;
    avgScore = avgScore.toFixed(1);

    var scoreTotal = document.getElementById('scoreTotal');
    scoreTotal.value = totalscore.toString();

    var scoreAvg = document.getElementById('scoreAvg');
    scoreAvg.value = avgScore.toString();

    avgScore = parseFloat(avgScore);

    if (avgScore <= 150 && avgScore >= 120)
      finalScore = "A";
    else if (avgScore < 120 && avgScore >= 100)
      finalScore = "B";
    else if (avgScore < 100 && avgScore >= 80)
      finalScore = "C";
    else if (avgScore < 80 && avgScore >= 60)
      finalScore = "D";
    else if (avgScore < 60)
      finalScore = "F";

    var scoreFinal = document.getElementById("scoreFinal")
    scoreFinal.value = finalScore
  } else {
    //If not all inputted test scores are valid, then create an alert box to display an error message
    alert(message);
  }
}; //end of processEntries function

//each time when calculate button is clicked, inputted test scores will be evaluated and 
$("calculate").onclick = function() {
  if (numInputs > 0 && numInputs < 6)
    processEntries();
};
$("numscores").focus();

@import url(http://fonts.googleapis.com/css?family=Wellfleet);
body {
  font-family: 'Wellfleet', Arial, Helvetica, sans-serif;
  background-color: white;
  margin: 0 auto;
  width: 60%;
  min-width: 600px;
  border: 3px solid blue;
  padding: 0 1em .5em;
}

h1 {
  color: blue;
  margin: .5em 0;
}

#teacher {
  float: right;
  margin: 0px 30px 0px 0px;
}

label {
  float: left;
  width: 10em;
  text-align: right;
  margin-bottom: .5em;
}

input {
  width: 5em;
  margin-left: 1em;
  margin-bottom: .5em;
}

input.error {
  background-color: yellow;
}

#s1 {
  display: inline-block;
}

#s1 input {
  vertical-align: center;
  float: left;
}

<!DOCTYPE html>
<html>

<head>
  <meta charset="UTF-8">
  <title>Test Score App</title>
  <link rel="stylesheet" href="score.css">
</head>

<body>
  <main>
    <h2>The Test Scores App</h2>
    <img src="teacher.png" id="teacher" alt="teacher" width="177" height="277">

    <div id="s1">
      <label for="numscores">How many tests you want to consider?</label>
      <input type='number' id='numscores' min='1' max='10' value='1'>
    </div>

    <div id="testInputs">
      <label for="score1">Test-1:</label>
      <input type='number' id='score1' value='150' /><br>
    </div>

    <div id='result'>
      <label for="scoreTotal">Total Points:</label>
      <input type="number" id="scoreTotal" disabled><br>

      <label for="scoreAvg">Avg Grade:</label>
      <input type="number" id="scoreAvg" disabled><br>

      <label for="scoreFinal">Final Letter Grade:</label>
      <input type="text" id="scoreFinal" disabled><br>

      <label>&nbsp;</label>
      <input type="button" id="calculate" value="Calculate">
    </div>

  </main>
  <script src="testScoreV2.js">
  </script>
</body>

</html>