Binding multiple events to a listener (without JQuery)?

Question

While working with browser events, I've started incorporating Safari's touchEvents for mobile devices. I find that addEventListeners are stacking up with conditionals. This project can't use JQuery.

A standard event listener:

/* option 1 */
window.addEventListener('mousemove', this.mouseMoveHandler, false);
window.addEventListener('touchmove', this.mouseMoveHandler, false);

/* option 2, only enables the required event */
var isTouchEnabled = window.Touch || false;
window.addEventListener(isTouchEnabled ? 'touchmove' : 'mousemove', this.mouseMoveHandler, false);

JQuery's bind allows multiple events, like so:

$(window).bind('mousemove touchmove', function(e) {
    //do something;
});

Is there a way to combine the two event listeners as in the JQuery example? ex:

window.addEventListener('mousemove touchmove', this.mouseMoveHandler, false);

Any suggestions or tips are appreciated!

Answer 1

Some compact syntax that achieves the desired result, POJS:

   "mousemove touchmove".split(" ").forEach(function(e){
      window.addEventListener(e,mouseMoveHandler,false);
    });

Answer 2

In POJS, you add one listener at a time. It is not common to add the same listener for two different events on the same element. You could write your own small function to do the job, e.g.:

/* Add one or more listeners to an element
** @param {DOMElement} element - DOM element to add listeners to
** @param {string} eventNames - space separated list of event names, e.g. 'click change'
** @param {Function} listener - function to attach for each event as a listener
*/
function addListenerMulti(element, eventNames, listener) {
  var events = eventNames.split(' ');
  for (var i=0, iLen=events.length; i<iLen; i++) {
    element.addEventListener(events[i], listener, false);
  }
}

addListenerMulti(window, 'mousemove touchmove', function(){…});

Hopefully it shows the concept.

Edit 2016-02-25

Dalgard's comment caused me to revisit this. I guess adding the same listener for multiple events on the one element is more common now to cover the various interface types in use, and Isaac's answer offers a good use of built–in methods to reduce the code (though less code is, of itself, not necessarily a bonus). Extended with ECMAScript 2015 arrow functions gives:

function addListenerMulti(el, s, fn) {
  s.split(' ').forEach(e => el.addEventListener(e, fn, false));
}

A similar strategy could add the same listener to multiple elements, but the need to do that might be an indicator for event delegation.

Answer 3

Cleaning up Isaac's answer:

['mousemove', 'touchmove'].forEach(function(e) {
  window.addEventListener(e, mouseMoveHandler);
});

EDIT

ES6 helper function:

function addMultipleEventListener(element, events, handler) {
  events.forEach(e => element.addEventListener(e, handler))
}

Answer 4

For me; this code works fine and is the shortest code to handle multiple events with same (inline) functions.

var eventList = ["change", "keyup", "paste", "input", "propertychange", "..."];
for(event of eventList) {
    element.addEventListener(event, function() {
        // your function body...
        console.log("you inserted things by paste or typing etc.");
    });
}

Answer 5

ES2015:

let el = document.getElementById("el");
let handler =()=> console.log("changed");
['change', 'keyup', 'cut'].forEach(event => el.addEventListener(event, handler));

Answer 6

I have a simpler solution for you:

window.onload = window.onresize = (event) => {
    //Your Code Here
}

I've tested this an it works great, on the plus side it's compact and uncomplicated like the other examples here.

Answer 7

One way how to do it:

const troll = document.getElementById('troll');

['mousedown', 'mouseup'].forEach(type => {
 if (type === 'mousedown') {
  troll.addEventListener(type, () => console.log('Mouse is down'));
 }
        else if (type === 'mouseup') {
                troll.addEventListener(type, () => console.log('Mouse is up'));
        }
});

img {
  width: 100px;
  cursor: pointer;
}

<div id="troll">
  <img src="http://images.mmorpg.com/features/7909/images/Troll.png" alt="Troll">
</div>

Answer 8

You can also use prototypes to bind your custom function to all elements

Node.prototype.addEventListeners = function(eventNames, eventFunction){
    for (eventName of eventNames.split(' '))
        this.addEventListener(eventName, eventFunction);
}

Then use it

document.body.addEventListeners("mousedown touchdown", myFunction)

Answer 9

AddEventListener take a simple string that represents event.type. So You need to write a custom function to iterate over multiple events.

This is being handled in jQuery by using .split(" ") and then iterating over the list to set the eventListeners for each types.

    // Add elem as a property of the handle function
    // This is to prevent a memory leak with non-native events in IE.
    eventHandle.elem = elem;

    // Handle multiple events separated by a space
    // jQuery(...).bind("mouseover mouseout", fn);
    types = types.split(" ");  

    var type, i = 0, namespaces;

    while ( (type = types[ i++ ]) ) {  <-- iterates thru 1 by 1

Answer 10

// BAD: One for each event - Repeat code
textarea.addEventListener('keypress', (event) => callPreview);
textarea.addEventListener('change', (event) => callPreview);

// GOOD: One run for multiple events
"keypress change".split(" ").forEach((eventName) => textarea.addEventListener(eventName, callPreview));