javascript - addEventListener repeats itself - Stack Overflow

admin管理员组

文章数量:1434014

I click <a>, it shows its id, but if I click the <a> again, it shows alert()twice, if I click it again, it shows alert() 3 times and it goes like that. How can I prevent repeating itself?

<a id="5" class="accRoom" onclick="dynamicLink()">5</a>
<a id="6" class="accRoom" onclick="dynamicLink()">6</a>

dynamicLink()function in a .js folder

function dynamicLink() {
    var x = document.getElementsByClassName("accRoom");
    for (var i = 0; i < x.length; i++) {
        x[i].addEventListener("click", function() {
            alert(this.id);
        }, false);
    }
}

I click <a>, it shows its id, but if I click the <a> again, it shows alert()twice, if I click it again, it shows alert() 3 times and it goes like that. How can I prevent repeating itself?

<a id="5" class="accRoom" onclick="dynamicLink()">5</a>
<a id="6" class="accRoom" onclick="dynamicLink()">6</a>

dynamicLink()function in a .js folder

function dynamicLink() {
    var x = document.getElementsByClassName("accRoom");
    for (var i = 0; i < x.length; i++) {
        x[i].addEventListener("click", function() {
            alert(this.id);
        }, false);
    }
}

• javascript

Share Improve this question Follow asked Dec 22, 2016 at 10:49 EnissEniss 91333 gold badges2323 silver badges4242 bronze badges 2

• How about not attaching a new event listener whenever the event listener is invoked? – Oliver Salzburg Commented Dec 22, 2016 at 10:51
• becuase every time you click on the <a> tag you add a new eventListener. – Kevin Kloet Commented Dec 22, 2016 at 10:51

Add a ment  | 

3 Answers 3

Sorted by: Reset to default 3

That happen because everytime you click your script will attach the click event to all the elements with class accRoom, you've just to attach the click one time :

var x = document.getElementsByClassName("accRoom");
for (var i = 0; i < x.length; i++) {
    x[i].addEventListener("click", function() {
        alert(this.id);
    }, false);
}

Then the html should looks like :

<a id="5" class="accRoom">5</a>
<a id="6" class="accRoom">6</a>

Hope will help you.

var x = document.getElementsByClassName("accRoom");

function eventFunction() {
  alert(this.id);
}
for (var i = 0; i < x.length; i++) {
  x[i].removeEventListener('click',eventFunction,false);
  x[i].addEventListener("click",eventFunction, false);
}

<a id="5" class="accRoom">5</a>
<a id="6" class="accRoom">6</a>

Or you could just send the clicked element as object this to the function onclick :

//This link was added dynamically
document.body.innerHTML += '<a id="7" class="accRoom" onclick="dynamicLink(this)">7</a>';

function dynamicLink(_this) {
  alert(_this.id);
}

<a id="5" class="accRoom" onclick="dynamicLink(this)">5</a>
<a id="6" class="accRoom" onclick="dynamicLink(this)">6</a>

The function dynamicLink is attaching an anonymous function (that does an alert) to the click event of every element with CSS class 'accRoom'.

The problem is that it is also attached to the click event. So each time you click it will attach another function to the click event, and so...

you can avoid that behaviour by removing the onclick attribute on 'accRoom' links and calling dynamicLink after the dom is loaded.

HTML:

<a id="5" class="accRoom">5</a>
<a id="6" class="accRoom">6</a>

JS:

var x = document.getElementsByClassName("accRoom");
for (var i = 0; i < x.length; i++) {
    x[i].addEventListener("click", function() {
        alert(this.id);
    }, false);
}
document.addEventListener("DOMContentLoaded", addDynamicLinks)

Hope it helps

Don't use anonymous function

function awesomeAlert(){
   alert(this.id);
}

function dynamicLink() {
    var x = document.getElementsByClassName("accRoom");
    for (var i = 0; i < x.length; i++) {
        x[i].removeEventListener("click", awesomeAlert);
        x[i].addEventListener("click", awesomeAlert, false);
    }
}

Maybe you don't care but there are a lot of better ways to set listeners, and in the code above there is room to improve and that is another story.

Have fun

本文标签： javascriptaddEventListener repeats itselfStack Overflow