Javascript/DOM: How to remove all events of a DOM object?

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.

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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:

1. Don't use a function that returns a function. Use the function directly:

    function handler() {
        dosomething();
    }
   
    div.addEventListener('click',handler,false);
   

2. 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()})