event.stopPropagation（）在Javascript中未结束冒泡

Question

I am starting to learn how this bubbling works in Javascript. Now my problem is, I guess I don't understand it completely! I am running an onclick in HTML (Which looks like this:

onclick="checkboxhit(<?php echo $allmail[$key]["mailid"]; ?>)"

), and it is running both the If and Else statements. Basically I am just trying to check WHEN and WHEN NOT check boxs are clicked. Here is the Javascript I am using:

listofmailids = [];
function checkboxhit(mailid) {
    if (listofmailids.indexOf(mailid) == -1) {
        listofmailids.push(mailid);
        $("#deletemail").css("color", "#474747");
        event.stopPropagation()
    }
    else {
        listofmailids.splice(listofmailids.indexOf(mailid), 1);
        if (listofmailids.length == -1) {
            $("#deletemail").css("color", "#A3A3A3");
        }
        event.stopPropagation()
    }
}

Yet the event.stopPropagation() is not stopping both the If and Else statements from executing. How could I fix this? Thank you!

Answer 1

When using onclick , if you want the event object, you need to explicitly pass it

onclick="checkboxhit(<?= json_encode($allmail[$key]['mailid']) ?>, event)"

and in your function

function checkboxhit(mailid, e) {
    e.stopPropagation();
    // etc

json_encode() will ensure the $allmail[$key]['mailid'] value is safe for use as a JavaScript literal.

---

If you want to stop propagation and prevent the default action, you can use a falsy return value like so

onclick="return checkboxhit(...)"

and in your function

return false;

Answer 2

return false is sufficient to stop bubbling as long as there is no JavaScript run-time error prior to reaching the false return.

Explicit passing the event parameter could be done in a more reliable fashion:

<a id="test">...</a>
<script>
function checkboxhit(mailid){
  return function(e){
    if (e) e.stopPropagation;
    ...
  }
}
document.getElementById('test').onclick=checkboxhit('123');
</script>

The above code runs in IE as well. The chosen answer will cause an error because "e" is not defined.

Answer 3

You should be using event listeners instead of inline handlers. The Event object is added automatically in that case...

Anyway, consider the following - it will behave exactly as you expect :)

<div id="outer">
  <button id="test">click me</button>
</div>

then...

document.getElementById('test').addEventListener('click', function (ev) {
  ev.stopPropagation()
}, false)

document.getElementById('outer').addEventListener('click', function (ev) {
  // never called...
}, false)