如何确定ul中的哪个li被单击？

Question

I'm making a quiz game in HTML/JavaScript which selects questions at random and adds the question and answer to the page ( document.getElementById, innerHTML etc.)

I want to add a click listener so when an answer is clicked it will determine if it is correct or not. How should I set up this listener (or listeners?) to distinguish between li s.

JavaScript

var elementQuestion = document.getElementById("question"); 
var elementAnswers = document.getElementById("answers"); 
elementQuestion.innerHTML = question[currentQuestion]; 
for(a = 0; a < answers[currentQuestion].length; a++) {
    var li = document.createElement("li");
    li.innerHTML = answers[currentQuestion][a];
    elementAnswers.appendChild(li);
}

HTML

<!-- Question -->
<p id="question"> </p>
<!-- Answer Array -->
<ul id="answers"> </ul>

(I get the feeling I'm missing something obvious...) Thanks

Answer 1

When you add your answer, you can also add an EventListener for that:

elementAnswers.addEventListener("click", been_clicked, true);

In the callback funktion "been_clicked" you can refer to the Element that handled the Event (here: the ul-node) as "this", and to the Element that was clicked as "e.target":

function been_clicked(e) {
   alert("You clicked '" + e.target.innerHTML + "'");
}

See http://jsfiddle.net/bjelline/7kSw5/ for a working demo.

Answer 2

Insert this into the loop:

li.onclick=create_on_click_function(li);

And add a new function, that will generate onclick callback function:

function create_on_click_function(element){

      return function(){
            alert(element.innerHTML + ' clicked');
      }
}

Add appropriate parameters to determine, whether the id of the clicked <li> element is equal to answer id.

Answer 3

If you add an id to each <li> (like answer_0, answer_1, etc.), you can have a single listener on the <ul> , to since events on the list items will bubble up:

var elementQuestion = document.getElementById("question"); 
var elementAnswers = document.getElementById("answers"); 
elementQuestion.innerHTML = question[currentQuestion]; 
for(a = 0; a < answers[currentQuestion].length; a++) {
    var li = document.createElement("li");
    li.innerHTML = answers[currentQuestion][a];
    li.id = "answer_" + a
    elementAnswers.appendChild(li);
}
elementAnswers.addEventListener("click", function(e) {
    alert("Clicked on " + e.target.id);
});