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HTML/Javascript Radio Button Quiz

 原文  2019-09-02 19:08:27  6   3    javascript/ html

Question

I'm trying to validate the radio buttons so that an error pops up when it's not checked.

However the error won't disappear unless I select an option from the Question 2 set and nothing from Question 1.

I'm trying to have both messages pop up for both questions if unchecked and and individually disappear when something is selected for that question 

 //Javascript var answers = ["A","C"], total = answers.length; function getCheckedValue(radioName) { var radios = document.getElementsByName(radioName); var errorSpan = document.getElementById("choice_error"); var isChecked = false; errorSpan.innerHTML = ""; for (var y = 0; y < radios.length; y++) { if(radios[y].checked) { isChecked = true; return radios[y].value } else if(!radios[y].checked) { isChecked = false; errorSpan.innerHTML = "Please select a choice."; } } return isChecked; } function getScore() { var score = 0; for (var i = 0; i < total; i++) { document.getElementById("flag"+i).innerHTML = ""; if(getCheckedValue("choice"+i) == answers[i]) { score += 1; document.getElementById("flag"+i).innerHTML = "Your answer is correct."; } else if(getCheckedValue("choice"+i) != answers[i]) { document.getElementById("flag"+i).innerHTML = "Your answer is incorrect."; } } return score; } function returnScore() { var x = document.getElementById("myText").value; document.getElementById("results").innerHTML = x + ", your score is " + getScore() + "/" + total; } 
 <!--HTML --> <!DOCTYPE html> <html lang="en"> <head> <title>Disney Quiz</title> <meta charset="utf-8"> <meta name="viewport" content="width=device-width, initial-scale=1"> <link rel="icon" href="images/favicon.ico"> <link rel="stylesheet" href="css/normalize.css"> <link rel="stylesheet" href="css/main.css"> <link href="https://fonts.googleapis.com/css?family=Roboto" rel="stylesheet"> <script src="scripts/quiz.js"></script> </head> <body> <header><h1>Disney Quiz</h1></header> <main> <p>Click on the correct answer for each question and submit your results.</p> <form> <fieldset> <legend>Trivia Questions</legend> <label> Enter your Name</label> <input type="text" id="myText" name="fieldName" placeholder="First Last"value=""><br> <section id="radio1"> <p> Question 1) What was Walt Disney's first character he created? <span id="choice_error"></span></p> <input type="radio" name="choice0" value="A">Oswald the Lucky Rabbit<br> <input type="radio" name="choice0" value="B">Donald Duck<br> <input type="radio" name="choice0" value="C">Mickey Mouse<br> <input type="radio" name="choice0" value="D">Goofy<br> <p id="flag0"></p> </section> <section id="radio2"> <p> Question 2) Snow White was the first ____ to ever be produced successfully. <span id="choice_error"></span></p></p> <input type="radio" name="choice1" value="A">Movie<br> <input type="radio" name="choice1" value="B">Live-Action<br> <input type="radio" name="choice1" value="C">Cel-animated Film<br> <input type="radio" name="choice1" value="D">Cartoon<br> <p id="flag1"><p> </section> <br> <input type="button" onclick="returnScore()" value="Show Results"> <input type="button" onclick="window.location.href = 'index.html';" value="Review"> <p id="results"></p> </fieldset> </form> </main> <aside> </aside> <footer> <p align="center"> Project 4 - Fall 2018 </p> </footer> </body> </html>

3 answers

solution1
 1  2019-09-02 19:26:26

In your code both error spans have the same ID "choice_error". No two html elements should have the same id, as then the browser won't be able to differentiate them.

If you want to access both error span elements, you can give each of them a ccs class "choice_error" and call the method document.getElementsByClassName().

Also you need to clear the error span inside the loop 

 function getCheckedValue(radioName) { var radios = document.getElementsByName(radioName); var errorSpans = document.getElementsByClassName("choise_error"); var isChecked = false; for (var y = 0; y < radios.length; y++) { errorSpans[y].innerHTML= ""; // clear the span if(radios[y].checked) { isChecked = true; return radios[y].value } else if(!radios[y].checked) { isChecked = false; errorSpans[y].innerHTML = "Please select a choice."; // error message } } return isChecked; }

solution2
 1 ACCPTED  2019-09-02 19:28:52

fastest method:

HTML : 

<span id="choice_error_choice0"></span>
<!-- ... -->
<span id="choice_error_choice1"></span>

JS : 

function getCheckedValue(radioName)
{
    let isChecked = true;
    let exist = document.querySelector(`input[name='${radioName}']:checked`);
    let choice_error = document.getElementById('choice_error_'+radioName);

    choice_error.innerHTML = "";

    if (exist == null)
    {
        isChecked = false;
        choice_error.innerHTML = "Please select a choice.";
    }

    return isChecked;

}

solution3
 1  2019-09-02 23:44:28

I've tidied a couple of things up. Using label for a start.

The main difference is I now use a parent question id to group our answers and change to class for choice_error .

Then I've use document.querySelector to find the checked answer and set the child error messages display style. 

 //Javascript var answers = ["A", "C"], total = answers.length; function getAnswer(QuestionId) { //Get the selected answer radio button var answer = document.querySelector("#" + QuestionId + " input[type=radio]:checked"); //It there isn't one if (answer === null) { //show the error mesage document.querySelector("#" + QuestionId + " .choice_error").style.display = "inline"; } else { //Otherwise hide the message document.querySelector("#" + QuestionId + " .choice_error").style.display = ""; //And set the answer value answer = answer.value; } return answer; } function getScore() { var score = 0; for (var i = 0; i < total; i++) { document.getElementById("flag" + i).innerHTML = ""; if (getAnswer("radio" + (i + 1)) == answers[i]) { score += 1; document.getElementById("flag" + i).innerHTML = "Your answer is correct."; } /*No need to check again, it either matches or doesn't*/ else { document.getElementById("flag" + i).innerHTML = "Your answer is incorrect."; } } return score; } function returnScore() { var x = document.getElementById("myText").value; document.getElementById("results").innerHTML = x + ", your score is " + getScore() + "/" + total; } 
 .questions label { display: block; } .choice_error { color: red; display: none; } 
 <!--HTML --> <!DOCTYPE html> <html lang="en"> <head> <title>Disney Quiz</title> <meta charset="utf-8"> <meta name="viewport" content="width=device-width, initial-scale=1"> <link rel="icon" href="images/favicon.ico"> <link rel="stylesheet" href="css/normalize.css"> <link rel="stylesheet" href="css/main.css"> <link href="https://fonts.googleapis.com/css?family=Roboto" rel="stylesheet"> <script src="scripts/quiz.js"></script> </head> <body> <header> <h1>Disney Quiz</h1> </header> <main> <p>Click on the correct answer for each question and submit your results.</p> <form> <fieldset> <legend>Trivia Questions</legend> <label> Enter your Name</label> <input type="text" id="myText" name="fieldName" placeholder="First Last" value=""><br> <section id="radio1" class="questions"> <p> Question 1) What was Walt Disney's first character he created? <span class="choice_error">Please select a choice</span></p> <label><input type="radio" name="choice0" value="A">Oswald the Lucky Rabbit</label> <label><input type="radio" name="choice0" value="B">Donald Duck</label> <label><input type="radio" name="choice0" value="C">Mickey Mouse</label> <label><input type="radio" name="choice0" value="D">Goofy</label> <p id="flag0"></p> </section> <section id="radio2" class="questions"> <p> Question 2) Snow White was the first ____ to ever be produced successfully. <span class="choice_error">Please select a choice</span></p> <label><input type="radio" name="choice1" value="A">Movie</label> <label><input type="radio" name="choice1" value="B">Live-Action</label> <label><input type="radio" name="choice1" value="C">Cel-animated Film</label> <label><input type="radio" name="choice1" value="D">Cartoon</label> <p id="flag1"> <p> </section> <br> <input type="button" onclick="returnScore()" value="Show Results"> <input type="button" onclick="window.location.href = 'index.html';" value="Review"> <p id="results"></p> </fieldset> </form> </main> <aside> </aside> <footer> <p align="center"> Project 4 - Fall 2018 </p> </footer> </body> </html>

We could refactor this some more, let one method handle manipulating the question related actions. 

 //Javascript var answers = ["A", "C"], total = answers.length; function checkAnswer(QuestionId, Answer) { var isCorrect = false; var questionElement = document.getElementById(QuestionId); //Get the selected answer radio button var answerElement = questionElement.querySelector("input[type=radio]:checked"); //It there isn't one if (answerElement === null) { //show the error mesage questionElement.querySelector(".choice_error").style.display = "inline"; questionElement.querySelector("[id^=flag]").innerHTML = ""; } else { //Otherwise hide the message questionElement.querySelector(".choice_error").style.display = ""; //And chcek answer isCorrect = Answer == answerElement.value; questionElement.querySelector("[id^=flag]").innerHTML = "Your answer is " + (isCorrect ? "correct" : "incorrect"); } return isCorrect; } function getScore() { var score = 0; for (var i = 0; i < total; i++) { if(checkAnswer("radio" + (i + 1), answers[i])) { score++;} } return score; } function returnScore() { var x = document.getElementById("myText").value; document.getElementById("results").innerHTML = x + ", your score is " + getScore() + "/" + total; } 
 .questions label { display: block; } .choice_error { color: red; display: none; } 
 <!--HTML --> <!DOCTYPE html> <html lang="en"> <head> <title>Disney Quiz</title> <meta charset="utf-8"> <meta name="viewport" content="width=device-width, initial-scale=1"> <link rel="icon" href="images/favicon.ico"> <link rel="stylesheet" href="css/normalize.css"> <link rel="stylesheet" href="css/main.css"> <link href="https://fonts.googleapis.com/css?family=Roboto" rel="stylesheet"> <script src="scripts/quiz.js"></script> </head> <body> <header> <h1>Disney Quiz</h1> </header> <main> <p>Click on the correct answer for each question and submit your results.</p> <form> <fieldset> <legend>Trivia Questions</legend> <label> Enter your Name</label> <input type="text" id="myText" name="fieldName" placeholder="First Last" value=""><br> <section id="radio1" class="questions"> <p> Question 1) What was Walt Disney's first character he created? <span class="choice_error">Please select a choice</span></p> <label><input type="radio" name="choice0" value="A">Oswald the Lucky Rabbit</label> <label><input type="radio" name="choice0" value="B">Donald Duck</label> <label><input type="radio" name="choice0" value="C">Mickey Mouse</label> <label><input type="radio" name="choice0" value="D">Goofy</label> <p id="flag0"></p> </section> <section id="radio2" class="questions"> <p> Question 2) Snow White was the first ____ to ever be produced successfully. <span class="choice_error">Please select a choice</span></p> <label><input type="radio" name="choice1" value="A">Movie</label> <label><input type="radio" name="choice1" value="B">Live-Action</label> <label><input type="radio" name="choice1" value="C">Cel-animated Film</label> <label><input type="radio" name="choice1" value="D">Cartoon</label> <p id="flag1"> <p> </section> <br> <input type="button" onclick="returnScore()" value="Show Results"> <input type="button" onclick="window.location.href = 'index.html';" value="Review"> <p id="results"></p> </fieldset> </form> </main> <aside> </aside> <footer> <p align="center"> Project 4 - Fall 2018 </p> </footer> </body> </html>

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