Related
Just question: Is there any way to completely remove all events of an object, e.g. a div?
EDIT: I'm adding per div.addEventListener('click',eventReturner(),false); an event.
function eventReturner() {
return function() {
dosomething();
};
}
EDIT2: I found a way, which is working, but not possible to use for my case:
var returnedFunction;
function addit() {
var div = document.getElementById('div');
returnedFunction = eventReturner();
div.addEventListener('click',returnedFunction,false); //You HAVE to take here a var and not the direct call to eventReturner(), because the function address must be the same, and it would change, if the function was called again.
}
function removeit() {
var div = document.getElementById('div');
div.removeEventListener('click',returnedFunction,false);
}
I am not sure what you mean with remove all events. Remove all handlers for a specific type of event or all event handlers for one type?
Remove all event handlers
If you want to remove all event handlers (of any type), you could clone the element and replace it with its clone:
var clone = element.cloneNode(true);
Note: This will preserve attributes and children, but it will not preserve any changes to DOM properties.
Remove "anonymous" event handlers of specific type
The other way is to use removeEventListener() but I guess you already tried this and it didn't work. Here is the catch:
Calling addEventListener to an anonymous function creates a new listener each time. Calling removeEventListener to an anonymous function has no effect. An anonymous function creates a unique object each time it is called, it is not a reference to an existing object though it may call one. When adding an event listener in this manner be sure it is added only once, it is permanent (cannot be removed) until the object it was added to, is destroyed.
You are essentially passing an anonymous function to addEventListener as eventReturner returns a function.
You have two possibilities to solve this:
Don't use a function that returns a function. Use the function directly:
function handler() {
dosomething();
}
div.addEventListener('click',handler,false);
Create a wrapper for addEventListener that stores a reference to the returned function and create some weird removeAllEvents function:
var _eventHandlers = {}; // somewhere global
const addListener = (node, event, handler, capture = false) => {
if (!(event in _eventHandlers)) {
_eventHandlers[event] = []
}
// here we track the events and their nodes (note that we cannot
// use node as Object keys, as they'd get coerced into a string
_eventHandlers[event].push({ node: node, handler: handler, capture: capture })
node.addEventListener(event, handler, capture)
}
const removeAllListeners = (targetNode, event) => {
// remove listeners from the matching nodes
_eventHandlers[event]
.filter(({ node }) => node === targetNode)
.forEach(({ node, handler, capture }) => node.removeEventListener(event, handler, capture))
// update _eventHandlers global
_eventHandlers[event] = _eventHandlers[event].filter(
({ node }) => node !== targetNode,
)
}
And then you could use it with:
addListener(div, 'click', eventReturner(), false)
// and later
removeAllListeners(div, 'click')
DEMO
Note: If your code runs for a long time and you are creating and removing a lot of elements, you would have to make sure to remove the elements contained in _eventHandlers when you destroy them.
This will remove all listeners from children but will be slow for large pages. Brutally simple to write.
element.outerHTML = element.outerHTML;
Use the event listener's own function remove(). For example:
getEventListeners().click.forEach((e)=>{e.remove()})
As corwin.amber says, there are differences between Webkit an others.
In Chrome:
getEventListeners(document);
Which gives you an Object with all the existing event listeners:
Object
click: Array[1]
closePopups: Array[1]
keyup: Array[1]
mouseout: Array[1]
mouseover: Array[1]
...
From here you can reach the listener you want to remove:
getEventListeners(document).copy[0].remove();
So All the event listeners:
for(var eventType in getEventListeners(document)) {
getEventListeners(document)[eventType].forEach(
function(o) { o.remove(); }
)
}
In Firefox
Is a little bit different because it uses a listener wrapper that contains no remove function. You have to get the listener you want to remove:
document.removeEventListener("copy", getEventListeners(document).copy[0].listener)
All the event listeners:
for(var eventType in getEventListeners(document)) {
getEventListeners(document)[eventType].forEach(
function(o) { document.removeEventListener(eventType, o.listener) }
)
}
I stumbled with this post trying to disable the annoying copy protection of a news website.
Enjoy!
You can add a hook function to intercept all calls to addEventHandler. The hook will push the handler to a list that can be used for cleanup. For example,
if (EventTarget.prototype.original_addEventListener == null) {
EventTarget.prototype.original_addEventListener = EventTarget.prototype.addEventListener;
function addEventListener_hook(typ, fn, opt) {
console.log('--- add event listener',this.nodeName,typ);
this.all_handlers = this.all_handlers || [];
this.all_handlers.push({typ,fn,opt});
this.original_addEventListener(typ, fn, opt);
}
EventTarget.prototype.addEventListener = addEventListener_hook;
}
You should insert this code near the top of your main web page (e.g. index.html). During cleanup, you can loop thru all_handlers, and call removeEventHandler for each. Don't worry about calling removeEventHandler multiple times with the same function. It is harmless.
For example,
function cleanup(elem) {
for (let t in elem) if (t.startsWith('on') && elem[t] != null) {
elem[t] = null;
console.log('cleanup removed listener from '+elem.nodeName,t);
}
for (let t of elem.all_handlers || []) {
elem.removeEventListener(t.typ, t.fn, t.opt);
console.log('cleanup removed listener from '+elem.nodeName,t.typ);
}
}
Note: for IE use Element instead of EventTarget, and change => to function, and various other things.
Clone the element and replace the element with its clone. Events are not cloned.
elem.replaceWith(elem.cloneNode(true));
This uses Node.cloneNode() to clone the elem DOM object, which ignores all event handlers (though, as Jan Turoň's answer notes, attributes like onclick="…" will remain). It then uses Element.replaceWith() to replace elem with that clone. Simple assignment to an anonymous clone wasn't working for me.
This should be faster and cleaner than redefining elem.outerHTML with itself (as proposed by pabombs's answer) but may be slower than answers that iterate through and purge each listener (noting that getEventListeners() seems available exclusively in Chrome's dev console—not elsewhere in Chrome, not at all on Firefox). Presumably, at some higher volume of listeners to clear, this non-loop solution becomes faster.
(This is a simplification of Felix Kling's answer with help from asheroto's comment to it.)
you can add function and remove all other click by assign them
btn1 = document.querySelector(".btn-1")
btn1.addEventListener("click" , _=>{console.log("hello")})
btn1.addEventListener("click" , _=>{console.log("How Are you ?")})
btn2 = document.querySelector(".btn-2")
btn2.onclick = _=>{console.log("Hello")}
btn2.onclick = _=>{console.log("Bye")}
<button class="btn-1">Hello to Me</button>
<button class="btn-2">Hello to Bye</button>
You can indeed remove all event handlers by cloning the node as #FelixKling suggests in his answer, however don't forget that
attribute event handlers are not affected by cloning
Having element like this
<div id="test" onclick="alert(42)">test</div>
will still alert on click after cloning. To remove this sort of events, you need to use removeAttribute method, in general
const removeAttEvents = el =>
[...el.attributes].forEach(att =>
att.name.startsWith("on") && el.removeAttribute(att.name)
);
Then having the test element above, calling removeAttEvents(test) gets rid of the click handler.
To complete the answers, here are real-world examples of removing events when you are visiting websites and don't have control over the HTML and JavaScript code generated.
Some annoying websites are preventing you to copy-paste usernames on login forms, which could easily be bypassed if the onpaste event was added with the onpaste="return false" HTML attribute.
In this case we just need to right click on the input field, select "Inspect element" in a browser like Firefox and remove the HTML attribute.
However, if the event was added through JavaScript like this:
document.getElementById("lyca_login_mobile_no").onpaste = function(){return false};
We will have to remove the event through JavaScript also:
document.getElementById("lyca_login_mobile_no").onpaste = null;
In my example, I used the ID "lyca_login_mobile_no" since it was the text input ID used by the website I was visiting.
Another way to remove the event (which will also remove all the events) is to remove the node and create a new one, like we have to do if addEventListener was used to add events using an anonymous function that we cannot remove with removeEventListener.
This can also be done through the browser console by inspecting an element, copying the HTML code, removing the HTML code and then pasting the HTML code at the same place.
It can also be done faster and automated through JavaScript:
var oldNode = document.getElementById("lyca_login_mobile_no");
var newNode = oldNode.cloneNode(true);
oldNode.parentNode.insertBefore(newNode, oldNode);
oldNode.parentNode.removeChild(oldNode);
Update: if the web app is made using a JavaScript framework like Angular, it looks the previous solutions are not working or breaking the app.
Another workaround to allow pasting would be to set the value through JavaScript:
document.getElementById("lyca_login_mobile_no").value = "username";
At the moment, I don't know if there is a way to remove all form validation and restriction events without breaking an app written entirely in JavaScript like Angular.
Update 2: There is also a way to remove a specific event that was added with addEventListener on a website we don't own, by using the getEventListeners function combined to removeEventListener like mentioned in the answer of Jmakuc. If getEventListeners does not exist like on Firefox, you can use a polyfill and inject the script on the page with Greasemonkey addon: https://github.com/colxi/getEventListeners/issues/1
The only easy way I found and worked is this:
Let's say we want to add 2 event listeners
const element = document.getElementById("element");
element.addEventListener('mouseover',
()=>{
// some task
});
element.addEventListener('mouseout',
()=>{
// some task
});
Now you can remove both of the elements by simply:
element.replaceWith(element.cloneNode(true));
Removing all the events on document:
One liner:
for (key in getEventListeners(document)) { getEventListeners(document)[key].forEach(function(c) { c.remove() }) }
Pretty version:
for (key in getEventListeners(document)) {
getEventListeners(document)[key].forEach(function(c) {
c.remove()
})
}
angular has a polyfill for this issue, you can check. I did not understand much but maybe it can help.
const REMOVE_ALL_LISTENERS_EVENT_LISTENER = 'removeAllListeners';
proto[REMOVE_ALL_LISTENERS_EVENT_LISTENER] = function () {
const target = this || _global;
const eventName = arguments[0];
if (!eventName) {
const keys = Object.keys(target);
for (let i = 0; i < keys.length; i++) {
const prop = keys[i];
const match = EVENT_NAME_SYMBOL_REGX.exec(prop);
let evtName = match && match[1];
// in nodejs EventEmitter, removeListener event is
// used for monitoring the removeListener call,
// so just keep removeListener eventListener until
// all other eventListeners are removed
if (evtName && evtName !== 'removeListener') {
this[REMOVE_ALL_LISTENERS_EVENT_LISTENER].call(this, evtName);
}
}
// remove removeListener listener finally
this[REMOVE_ALL_LISTENERS_EVENT_LISTENER].call(this, 'removeListener');
}
else {
const symbolEventNames = zoneSymbolEventNames$1[eventName];
if (symbolEventNames) {
const symbolEventName = symbolEventNames[FALSE_STR];
const symbolCaptureEventName = symbolEventNames[TRUE_STR];
const tasks = target[symbolEventName];
const captureTasks = target[symbolCaptureEventName];
if (tasks) {
const removeTasks = tasks.slice();
for (let i = 0; i < removeTasks.length; i++) {
const task = removeTasks[i];
let delegate = task.originalDelegate ? task.originalDelegate : task.callback;
this[REMOVE_EVENT_LISTENER].call(this, eventName, delegate, task.options);
}
}
if (captureTasks) {
const removeTasks = captureTasks.slice();
for (let i = 0; i < removeTasks.length; i++) {
const task = removeTasks[i];
let delegate = task.originalDelegate ? task.originalDelegate : task.callback;
this[REMOVE_EVENT_LISTENER].call(this, eventName, delegate, task.options);
}
}
}
}
if (returnTarget) {
return this;
}
};
....
You can add a helper function that clears event listener for example
function clearEventListener(element) {
const clonedElement = element.cloneNode(true);
element.replaceWith(clonedElement);
return clonedElement;
}
just pass in the element to the function and that's it...
Sub-class of EventTarget from the JavaScript WebAPI. Supports removing events without specifying a handler function reference.
class SmartEventTarget extends EventTarget {
constructor() {
super();
this.handlers = {};
}
addEventListener(name, handler) {
super.addEventListener(name, handler);
if (!this.handlers[name]) {
this.handlers[name] = new Set();
}
this.handlers[name].add(handler);
}
removeEventListener(name, handler) {
if (handler) {
super.removeEventListener(name, handler);
this.handlers[name].delete(handler);
} else {
this.handlers[name].forEach(h => {
super.removeEventListener(name, h)
});
this.handlers[name].clear();
}
}
removeAllListeners(name) {
if (name) {
this.removeEventListener(name, null);
} else {
Object.keys(this.handlers).map(name => {
this.removeEventListener(name, null);
});
this.handlers = {};
}
}
}
See this Gist for unit tests. You can run the tests by simply copying the code from the Gist into your browser JS console and pressing enter.
Be sure to read strange JS from the internet before blindly pasting it into your console.
https://gist.github.com/angstyloop/504414aba95b61b98be0db580cb2a3b0
I know this is an old question but for me the only thing that worked was:
parentOfTheElement.innerHTML = parentOfTheElement.innerHTML;
While the other solutions do in fact remove all the listeners, I had problems adding new ones when using either the outerHTML trick or cloneNode()
May be the browser will do it for you if you do something like:
Copy the div and its attributes and insert it before the old one, then move the content from the old to the new and delete the old?
One method is to add a new event listener that calls e.stopImmediatePropagation().
var div = getElementsByTagName('div')[0]; /* first div found; you can use getElementById for more specific element */
div.onclick = null; // OR:
div.onclick = function(){};
//edit
I didn't knew what method are you using for attaching events. For addEventListener you can use this:
div.removeEventListener('click',functionName,false); // functionName is the name of your callback function
more details
So I am a super JS noob, I am not even sure I am asking this question properly, but...
I am trying to dynamically create buttons, then set their onclick event listeners to one of a set of predetermined functions. I want to be able to do this one of two ways, as follows:
var newInput = document.createElement('input');
newInput.parameters = "xyz";
document.getElementById("element").appendChild(newInput);
newInput.onclick = "funcsnip" + array[variable] + "()";
Or, alternatively,
var newInput = document.createElement('input');
newInput.parameters = "xyz";
document.getElementById("element").appendChild(newInput);
newInput.onclick = array[variable];
Where the array is stocked with "myFunction()" primitives.
I have no doubt there are a million things I "should" be doing, but I am happy with the majority of my code, I just want to know basically how to pass a string as a parameter for onclick, if that is possible.
Or, if it is not possible, another way to attach an onclick event to a dynamic input element.
Simpler and more elegant, the better. Thank you!
You can't pass a string to onclick listener. It should be a function. What you can do alternatively is to create a map of functions.
Let's say you have these functions available:
function oneFunc() { console.log('one');
function twoFunc() { console.log('two');
Then you can create a mapping:
var map = {
one : oneFunc,
two : twoFunc
};
So you can access oneFunc by calling map.one or map["one"].
Now solving your problem is straightforward
var newInput = document.createElement('input');
var variable = "one";
// var variable = "two";
newInput.parameters = "xyz";
document.getElementById("element").appendChild(newInput);
// You pass an actual function, but using a string parameter.
newInput.onclick = map[variable];
When you click a button, you will see "one" in the console.
If you have a string for every button that represents a function, you can write
var functionCollection = {
'stringOne': function() {
...
}
}
...
newInput.onclick = functionCollection[myStringValue];
or you could create one handler function and invoke it with the string type through binding, e.g.
function clickHandler(stringValue) {
switch (stringValue) {
case 'stringOne':
return someSpecialFunction();
...
}
}
...
newInput.onclick = clickHandler.bind(this, myStringValue);
Both newInput.setAttribute("onclick", "alert(1)") and newInput.setAttribute("onclick", "function() {alert(1) }" will work. Your code doesn't work because you're trying to set a function string on the onclick property, which expects a true function object.
Having said that, you really should use addEventListener, or an abstraction like jquery's on.
I`m attempting to bind an observable array of people two a two column responsive layout with click events using knockoutjs.
I have created a custom binding called TwoCol that loops through the array, and appends nodes to the DOM to create my suggested layout, but the click events are giving me trouble when I try to apply them in a custom binding nested in a loop.
I have played with it quite a bit, and encountered all types of results, but where I`m at now is calling my ~click~ event during binding, rather than on click.
http://jsfiddle.net/5SPVm/6/
HTML:
<div data-bind="TwoCol: Friends" id="" style="padding: 20px">
JAVASCRIPT:
function FriendsModel() {
var self = this;
this.Friends = ko.observableArray();
this.SelectedFriend = "";
this.SetSelected = function (person) {
alert(person);
self.SelectedFriend = person;
}
}
function isOdd(num) {
return num % 2;
}
ko.bindingHandlers.TwoCol = {
update: function (elem, valueAccessor) {
var i = 0;
var rowDiv;
var vFriends = ko.utils.unwrapObservable(valueAccessor());
$(elem).html('');
while (i < vFriends.length) {
//create row container every other iteration
if (!isOdd(i)) {
rowDiv = document.createElement("div");
$(rowDiv).addClass("row-fluid");
elem.appendChild(rowDiv);
}
//add column for every iteration
var colDiv = document.createElement("div");
$(colDiv).addClass("span6");
rowDiv.appendChild(colDiv);
//actual code has fairly complex button html here
var htmlDiv = document.createElement("div");
var htmlButton = vFriends[i]
htmlDiv.innerHTML = htmlButton;
colDiv.appendChild(htmlDiv);
//i think i need to add the event to the template too?
//$(htmlDiv).attr("data-bind", "click: { alert: $data }")
//it seems that the SetSelected Method is called while looping
ko.applyBindingsToDescendants(htmlDiv, { click: friends.SetSelected(vFriends[i]) });
i++;
}
return { controlsDescendantBindings: true };
}
}
var friends = new FriendsModel();
friends.Friends.push('bob');
friends.Friends.push('rob');
friends.Friends.push('mob');
friends.Friends.push('lob');
ko.applyBindings(friends);
I don't think you're using ko.applyBindingsToDescendants correctly. I admit I'm a little confused as to the meaning of some of the values in your code, so I may have interpreted something incorrectly.
Here's a fiddle where I think it's working the way you intended:
http://jsfiddle.net/5SPVm/7/
http://jsfiddle.net/5SPVm/8/
Notice if manually control descendant bindings (return { controlsDescendantBindings: true };), you need to set that up in the init callback, instead of update. The update callback is too late for that.
Quick rundown of the changes (edited):
Moved the controlsDescendantBindings into the init binding callback
Added the necessary parameter names to the binding param list to access additional values.
I re-enabled the html.attr call. Notice that now, because the binding context is set to the actual item, the SetSelected method doesn't exist at that level anymore, so it is necessary to use $parent.SetSelected.
$(htmlDiv).attr("data-bind", "click: $parent.SetSelected")
Fixed the ko.applyBindingsToDescendants call. This method takes a binding context, which is created from the current binding context, and also takes the element to apply the binding to. You don't want to reapply the binding, which is why this whole thing needs to be in the init handler.
var childBindingContext = bindingContext.createChildContext(vFriends[i]);
ko.applyBindingsToDescendants(childBindingContext, colDiv);
Just question: Is there any way to completely remove all events of an object, e.g. a div?
EDIT: I'm adding per div.addEventListener('click',eventReturner(),false); an event.
function eventReturner() {
return function() {
dosomething();
};
}
EDIT2: I found a way, which is working, but not possible to use for my case:
var returnedFunction;
function addit() {
var div = document.getElementById('div');
returnedFunction = eventReturner();
div.addEventListener('click',returnedFunction,false); //You HAVE to take here a var and not the direct call to eventReturner(), because the function address must be the same, and it would change, if the function was called again.
}
function removeit() {
var div = document.getElementById('div');
div.removeEventListener('click',returnedFunction,false);
}
I am not sure what you mean with remove all events. Remove all handlers for a specific type of event or all event handlers for one type?
Remove all event handlers
If you want to remove all event handlers (of any type), you could clone the element and replace it with its clone:
var clone = element.cloneNode(true);
Note: This will preserve attributes and children, but it will not preserve any changes to DOM properties.
Remove "anonymous" event handlers of specific type
The other way is to use removeEventListener() but I guess you already tried this and it didn't work. Here is the catch:
Calling addEventListener to an anonymous function creates a new listener each time. Calling removeEventListener to an anonymous function has no effect. An anonymous function creates a unique object each time it is called, it is not a reference to an existing object though it may call one. When adding an event listener in this manner be sure it is added only once, it is permanent (cannot be removed) until the object it was added to, is destroyed.
You are essentially passing an anonymous function to addEventListener as eventReturner returns a function.
You have two possibilities to solve this:
Don't use a function that returns a function. Use the function directly:
function handler() {
dosomething();
}
div.addEventListener('click',handler,false);
Create a wrapper for addEventListener that stores a reference to the returned function and create some weird removeAllEvents function:
var _eventHandlers = {}; // somewhere global
const addListener = (node, event, handler, capture = false) => {
if (!(event in _eventHandlers)) {
_eventHandlers[event] = []
}
// here we track the events and their nodes (note that we cannot
// use node as Object keys, as they'd get coerced into a string
_eventHandlers[event].push({ node: node, handler: handler, capture: capture })
node.addEventListener(event, handler, capture)
}
const removeAllListeners = (targetNode, event) => {
// remove listeners from the matching nodes
_eventHandlers[event]
.filter(({ node }) => node === targetNode)
.forEach(({ node, handler, capture }) => node.removeEventListener(event, handler, capture))
// update _eventHandlers global
_eventHandlers[event] = _eventHandlers[event].filter(
({ node }) => node !== targetNode,
)
}
And then you could use it with:
addListener(div, 'click', eventReturner(), false)
// and later
removeAllListeners(div, 'click')
DEMO
Note: If your code runs for a long time and you are creating and removing a lot of elements, you would have to make sure to remove the elements contained in _eventHandlers when you destroy them.
This will remove all listeners from children but will be slow for large pages. Brutally simple to write.
element.outerHTML = element.outerHTML;
Use the event listener's own function remove(). For example:
getEventListeners().click.forEach((e)=>{e.remove()})
As corwin.amber says, there are differences between Webkit an others.
In Chrome:
getEventListeners(document);
Which gives you an Object with all the existing event listeners:
Object
click: Array[1]
closePopups: Array[1]
keyup: Array[1]
mouseout: Array[1]
mouseover: Array[1]
...
From here you can reach the listener you want to remove:
getEventListeners(document).copy[0].remove();
So All the event listeners:
for(var eventType in getEventListeners(document)) {
getEventListeners(document)[eventType].forEach(
function(o) { o.remove(); }
)
}
In Firefox
Is a little bit different because it uses a listener wrapper that contains no remove function. You have to get the listener you want to remove:
document.removeEventListener("copy", getEventListeners(document).copy[0].listener)
All the event listeners:
for(var eventType in getEventListeners(document)) {
getEventListeners(document)[eventType].forEach(
function(o) { document.removeEventListener(eventType, o.listener) }
)
}
I stumbled with this post trying to disable the annoying copy protection of a news website.
Enjoy!
You can add a hook function to intercept all calls to addEventHandler. The hook will push the handler to a list that can be used for cleanup. For example,
if (EventTarget.prototype.original_addEventListener == null) {
EventTarget.prototype.original_addEventListener = EventTarget.prototype.addEventListener;
function addEventListener_hook(typ, fn, opt) {
console.log('--- add event listener',this.nodeName,typ);
this.all_handlers = this.all_handlers || [];
this.all_handlers.push({typ,fn,opt});
this.original_addEventListener(typ, fn, opt);
}
EventTarget.prototype.addEventListener = addEventListener_hook;
}
You should insert this code near the top of your main web page (e.g. index.html). During cleanup, you can loop thru all_handlers, and call removeEventHandler for each. Don't worry about calling removeEventHandler multiple times with the same function. It is harmless.
For example,
function cleanup(elem) {
for (let t in elem) if (t.startsWith('on') && elem[t] != null) {
elem[t] = null;
console.log('cleanup removed listener from '+elem.nodeName,t);
}
for (let t of elem.all_handlers || []) {
elem.removeEventListener(t.typ, t.fn, t.opt);
console.log('cleanup removed listener from '+elem.nodeName,t.typ);
}
}
Note: for IE use Element instead of EventTarget, and change => to function, and various other things.
Clone the element and replace the element with its clone. Events are not cloned.
elem.replaceWith(elem.cloneNode(true));
This uses Node.cloneNode() to clone the elem DOM object, which ignores all event handlers (though, as Jan Turoň's answer notes, attributes like onclick="…" will remain). It then uses Element.replaceWith() to replace elem with that clone. Simple assignment to an anonymous clone wasn't working for me.
This should be faster and cleaner than redefining elem.outerHTML with itself (as proposed by pabombs's answer) but may be slower than answers that iterate through and purge each listener (noting that getEventListeners() seems available exclusively in Chrome's dev console—not elsewhere in Chrome, not at all on Firefox). Presumably, at some higher volume of listeners to clear, this non-loop solution becomes faster.
(This is a simplification of Felix Kling's answer with help from asheroto's comment to it.)
you can add function and remove all other click by assign them
btn1 = document.querySelector(".btn-1")
btn1.addEventListener("click" , _=>{console.log("hello")})
btn1.addEventListener("click" , _=>{console.log("How Are you ?")})
btn2 = document.querySelector(".btn-2")
btn2.onclick = _=>{console.log("Hello")}
btn2.onclick = _=>{console.log("Bye")}
<button class="btn-1">Hello to Me</button>
<button class="btn-2">Hello to Bye</button>
You can indeed remove all event handlers by cloning the node as #FelixKling suggests in his answer, however don't forget that
attribute event handlers are not affected by cloning
Having element like this
<div id="test" onclick="alert(42)">test</div>
will still alert on click after cloning. To remove this sort of events, you need to use removeAttribute method, in general
const removeAttEvents = el =>
[...el.attributes].forEach(att =>
att.name.startsWith("on") && el.removeAttribute(att.name)
);
Then having the test element above, calling removeAttEvents(test) gets rid of the click handler.
To complete the answers, here are real-world examples of removing events when you are visiting websites and don't have control over the HTML and JavaScript code generated.
Some annoying websites are preventing you to copy-paste usernames on login forms, which could easily be bypassed if the onpaste event was added with the onpaste="return false" HTML attribute.
In this case we just need to right click on the input field, select "Inspect element" in a browser like Firefox and remove the HTML attribute.
However, if the event was added through JavaScript like this:
document.getElementById("lyca_login_mobile_no").onpaste = function(){return false};
We will have to remove the event through JavaScript also:
document.getElementById("lyca_login_mobile_no").onpaste = null;
In my example, I used the ID "lyca_login_mobile_no" since it was the text input ID used by the website I was visiting.
Another way to remove the event (which will also remove all the events) is to remove the node and create a new one, like we have to do if addEventListener was used to add events using an anonymous function that we cannot remove with removeEventListener.
This can also be done through the browser console by inspecting an element, copying the HTML code, removing the HTML code and then pasting the HTML code at the same place.
It can also be done faster and automated through JavaScript:
var oldNode = document.getElementById("lyca_login_mobile_no");
var newNode = oldNode.cloneNode(true);
oldNode.parentNode.insertBefore(newNode, oldNode);
oldNode.parentNode.removeChild(oldNode);
Update: if the web app is made using a JavaScript framework like Angular, it looks the previous solutions are not working or breaking the app.
Another workaround to allow pasting would be to set the value through JavaScript:
document.getElementById("lyca_login_mobile_no").value = "username";
At the moment, I don't know if there is a way to remove all form validation and restriction events without breaking an app written entirely in JavaScript like Angular.
Update 2: There is also a way to remove a specific event that was added with addEventListener on a website we don't own, by using the getEventListeners function combined to removeEventListener like mentioned in the answer of Jmakuc. If getEventListeners does not exist like on Firefox, you can use a polyfill and inject the script on the page with Greasemonkey addon: https://github.com/colxi/getEventListeners/issues/1
The only easy way I found and worked is this:
Let's say we want to add 2 event listeners
const element = document.getElementById("element");
element.addEventListener('mouseover',
()=>{
// some task
});
element.addEventListener('mouseout',
()=>{
// some task
});
Now you can remove both of the elements by simply:
element.replaceWith(element.cloneNode(true));
Removing all the events on document:
One liner:
for (key in getEventListeners(document)) { getEventListeners(document)[key].forEach(function(c) { c.remove() }) }
Pretty version:
for (key in getEventListeners(document)) {
getEventListeners(document)[key].forEach(function(c) {
c.remove()
})
}
angular has a polyfill for this issue, you can check. I did not understand much but maybe it can help.
const REMOVE_ALL_LISTENERS_EVENT_LISTENER = 'removeAllListeners';
proto[REMOVE_ALL_LISTENERS_EVENT_LISTENER] = function () {
const target = this || _global;
const eventName = arguments[0];
if (!eventName) {
const keys = Object.keys(target);
for (let i = 0; i < keys.length; i++) {
const prop = keys[i];
const match = EVENT_NAME_SYMBOL_REGX.exec(prop);
let evtName = match && match[1];
// in nodejs EventEmitter, removeListener event is
// used for monitoring the removeListener call,
// so just keep removeListener eventListener until
// all other eventListeners are removed
if (evtName && evtName !== 'removeListener') {
this[REMOVE_ALL_LISTENERS_EVENT_LISTENER].call(this, evtName);
}
}
// remove removeListener listener finally
this[REMOVE_ALL_LISTENERS_EVENT_LISTENER].call(this, 'removeListener');
}
else {
const symbolEventNames = zoneSymbolEventNames$1[eventName];
if (symbolEventNames) {
const symbolEventName = symbolEventNames[FALSE_STR];
const symbolCaptureEventName = symbolEventNames[TRUE_STR];
const tasks = target[symbolEventName];
const captureTasks = target[symbolCaptureEventName];
if (tasks) {
const removeTasks = tasks.slice();
for (let i = 0; i < removeTasks.length; i++) {
const task = removeTasks[i];
let delegate = task.originalDelegate ? task.originalDelegate : task.callback;
this[REMOVE_EVENT_LISTENER].call(this, eventName, delegate, task.options);
}
}
if (captureTasks) {
const removeTasks = captureTasks.slice();
for (let i = 0; i < removeTasks.length; i++) {
const task = removeTasks[i];
let delegate = task.originalDelegate ? task.originalDelegate : task.callback;
this[REMOVE_EVENT_LISTENER].call(this, eventName, delegate, task.options);
}
}
}
}
if (returnTarget) {
return this;
}
};
....
You can add a helper function that clears event listener for example
function clearEventListener(element) {
const clonedElement = element.cloneNode(true);
element.replaceWith(clonedElement);
return clonedElement;
}
just pass in the element to the function and that's it...
Sub-class of EventTarget from the JavaScript WebAPI. Supports removing events without specifying a handler function reference.
class SmartEventTarget extends EventTarget {
constructor() {
super();
this.handlers = {};
}
addEventListener(name, handler) {
super.addEventListener(name, handler);
if (!this.handlers[name]) {
this.handlers[name] = new Set();
}
this.handlers[name].add(handler);
}
removeEventListener(name, handler) {
if (handler) {
super.removeEventListener(name, handler);
this.handlers[name].delete(handler);
} else {
this.handlers[name].forEach(h => {
super.removeEventListener(name, h)
});
this.handlers[name].clear();
}
}
removeAllListeners(name) {
if (name) {
this.removeEventListener(name, null);
} else {
Object.keys(this.handlers).map(name => {
this.removeEventListener(name, null);
});
this.handlers = {};
}
}
}
See this Gist for unit tests. You can run the tests by simply copying the code from the Gist into your browser JS console and pressing enter.
Be sure to read strange JS from the internet before blindly pasting it into your console.
https://gist.github.com/angstyloop/504414aba95b61b98be0db580cb2a3b0
I know this is an old question but for me the only thing that worked was:
parentOfTheElement.innerHTML = parentOfTheElement.innerHTML;
While the other solutions do in fact remove all the listeners, I had problems adding new ones when using either the outerHTML trick or cloneNode()
May be the browser will do it for you if you do something like:
Copy the div and its attributes and insert it before the old one, then move the content from the old to the new and delete the old?
One method is to add a new event listener that calls e.stopImmediatePropagation().
var div = getElementsByTagName('div')[0]; /* first div found; you can use getElementById for more specific element */
div.onclick = null; // OR:
div.onclick = function(){};
//edit
I didn't knew what method are you using for attaching events. For addEventListener you can use this:
div.removeEventListener('click',functionName,false); // functionName is the name of your callback function
more details
Javascript is pretty shaky for me, and I can't seem to find the answer to this. I have some code along the lines of
var Scheduler = function(divid,startDate,mode){
this.setHeader = function(){
header.innerHTML = 'Show';
}
this.showScheduler = function period(){
...
}
};
My problem is, how do I put the onclick into the HTML so that it properly calls the showScheduler function for the appropriate instance of the current scheduler object that I'm working with?
I wouldn't do whatever it is you're doing the way you're doing it, but with the code the way you have it, I would do this (lots ofdo and doing :) ):
var Scheduler = function(divid, startDate, mode){
var that = this;
this.setHeader = function(){
header.innerHTML = 'Show';
header.firstChild.onclick = function() { that.showScheduler(1); };
}
this.showScheduler = function period(){
...
}
};
You should use a framework for this type of thing. If you don't use one then you gotta declare each instance of schedular as a global object, and you will need the name of the instance in order to call it from the link. Look at the following link
http://developer.yahoo.com/yui/examples/event/eventsimple.html
They only show a function being applied, but you can also do something like this
YAHOO.util.Event.addListener(myAnchorDom, "click", this.showScheduler,this,true);
Where myAnchorDom is the achor tag dom object. This will have showScheduler function execute within the scope of your scheduler object.
Instead of working with innerHTML use the DOM methods.
Try replacing this:
header.innerHTML = 'Show';
with this:
var x = this; // create a closure reference
var anchor = document.createElement('a');
anchor.href= '#';
anchor.innerHTML = 'Show';
anchor.onclick = function() { x.showScheduler(1); }; //don't use onclick in real life, use some real event binding from a library
header.appendChild(anchor);
Explanation:
The "this" in the original code refers to the element which fired the event, i.e. the anchor ("this' is notoriously problematic for things like, well, like this). The solution is to create a closure on the correct method (which is why you have to create something like the var x above) which then only leaves the problem of passing in the parameter which is accomplished by wrapping the method in another function.
Strictly speaking it would be much preferable to bind eventhandlers with the addEventListener/attachEvent pair (because direct event assignment precludes the ability to assign multiple handlers to one event) but it's best handled using a library like jquery if you're new to JS anyway.
You can add an event handler to the header object directly:
var me = this;
this.setHeader = function(){
header.innerHTML = 'Show';
header.addHandler("click", function(e) { me.showScheduler(1); });
}
Insite the passed function, this will refer to the header element.
var Scheduler = function(divid, startDate, mode)
{
var xthis = this;
this.setHeader = function()
{
var lnk = document.createElement("a");
lnk.addEventListener("click", xthis.showScheduler, false);
lnk.innerText = "Show";
lnk.setAttribute('href', "#");
header.appendChild(lnk);
}
this.showScheduler = function period(){
...
}
};
When using "this" inside the onclick attribute, you're actually referring to the anchor tag object. Try this and see if it works:
this.setHeader = function(){
header.innerHTML = 'Show';
}