Add a JavaScript Event to an Image With JavaScript - javascript

Ok so I'm going to try and make this as clear as possible. I want to write a function that when called will add an onmouseout attribute to an image.
Before the image is moused over.
<img src="myfile.jpg" onmouseover="function()" />
After
<img src="myfile.jpg" onmouseover="function()" onmouseout="anotherFunction()" />
I would also like to change the picture with function() and then onmouseout set the picture back to the original. I know how to change the pictures with onmouseover and onmouseout right in the image code but I'm trying to simplify this as I have to do the image changy thing about 100 times and I dont want to write out the code that many times. Gah I hope that was clear.

This is simpler than you may think:
function SetImageSource(ele, url) {
ele.src = url;
}
<img src="myfile.jpg"
onmouseover="SetImageSource(this, 'someURL')"
onmouseout="SetImageSource(this, 'someOtherURL')" />
Note: Inline JavaScript is not ideal. I suggest reading up on event handling in JS. More specifically, read about attaching to an event.
Edit per clarification
<img id="imgMyImage" src="myfile.jpg"
onmouseover="SetImageSource(this, 'someURL')"
onmouseout="SetImageSource(this, 'someOtherURL')" />
function AddEvent(html_element, event_name, event_function)
{
if(html_element.attachEvent) //Internet Explorer
html_element.attachEvent("on" + event_name, function() {event_function.call(html_element);});
else if(html_element.addEventListener) // Everything else
html_element.addEventListener(event_name, event_function, false);
}
AddEvent(document.getElementById('imgMyImage'),
'onmouseover',
// do something
);
Additional Information
See .addEventListener() on MDN
See .attachEvent() on MSDN

Here we go http://jsfiddle.net/5U9w9/2/
I'm going to update the jsFidle with more comments and will update the link here too.
javascript
// grab all the required element on the page
var img_all = document.getElementsByTagName('img');
// for every element do this
for (i=0; i< img_all.length; i++){
var img = img_all[i];
// set the required event on the element
// when the event of the element occurs, the associated function will be called with event object as it's argument.
// https://developer.mozilla.org/en-US/docs/Mozilla_event_reference
//img.addEventListener('mouseover', mouseover_handler, false);
AddEvent(img, 'mouseover', mouseover_handler)
//mouseout_handler will be called, on mouseout event
// img.addEventListener('mouseout', mouseout_handler, false);
AddEvent(img, 'mouseout', mouseout_handler)
}
function mouseover_handler(e){
// el is and event object and has various properties like clientX, clientY, srcElement, etc. you can check them by console.log(el)
console.log(e)
// to get the element i'm hovering, use
var element = e.srcElement;
//element is DOM element and can be manupulated
element.style.width="100px";
}
// similarly handler for an another event.
function mouseout_handler(e){
e.srcElement.style.width="50px";
}
​// cross-browser addEventListner
function AddEvent(html_element, event_name, event_function)
{
if(html_element.attachEvent) //Internet Explorer
html_element.attachEvent("on" + event_name, function() {event_function.call(html_element);});
else if(html_element.addEventListener) // Everything else
html_element.addEventListener(event_name, event_function, false);
}
Update
Use AddEvent in the place of addEventListner() for IE support.​ (CREDIT: #James Hill's answer)

Related

Change-Event for div [duplicate]

I want to run a function when a user edits the content of a div with contenteditable attribute. What's the equivalent of an onchange event?
I'm using jQuery so any solutions that uses jQuery is preferred. Thanks!
2022 update
As pointed out in the comments, this doesn't answer the question asked, which wanted the equivalent of the change event rather than the input event. However, I'll leave it here as is.
Original answer
I'd suggest attaching listeners to key events fired by the editable element, though you need to be aware that keydown and keypress events are fired before the content itself is changed. This won't cover every possible means of changing the content: the user can also use cut, copy and paste from the Edit or context browser menus, so you may want to handle the cut copy and paste events too. Also, the user can drop text or other content, so there are more events there (mouseup, for example). You may want to poll the element's contents as a fallback.
UPDATE 29 October 2014
The HTML5 input event is the answer in the long term. At the time of writing, it is supported for contenteditable elements in current Mozilla (from Firefox 14) and WebKit/Blink browsers, but not IE.
Demo:
document.getElementById("editor").addEventListener("input", function() {
console.log("input event fired");
}, false);
<div contenteditable="true" id="editor">Please type something in here</div>
Demo: http://jsfiddle.net/ch6yn/2691/
Here is a more efficient version which uses on for all contenteditables. It's based off the top answers here.
$('body').on('focus', '[contenteditable]', function() {
const $this = $(this);
$this.data('before', $this.html());
}).on('blur keyup paste input', '[contenteditable]', function() {
const $this = $(this);
if ($this.data('before') !== $this.html()) {
$this.data('before', $this.html());
$this.trigger('change');
}
});
The project is here: https://github.com/balupton/html5edit
Consider using MutationObserver. These observers are designed to react to changes in the DOM, and as a performant replacement to Mutation Events.
Pros:
Fires when any change occurs, which is difficult to achieve by listening to key events as suggested by other answers. For example, all of these work well: drag & drop, italicizing, copy/cut/paste through context menu.
Designed with performance in mind.
Simple, straightforward code. It's a lot easier to understand and debug code that listens to one event rather than code that listens to 10 events.
Google has an excellent mutation summary library which makes using MutationObservers very easy.
Cons:
Requires a very recent version of Firefox (14.0+), Chrome (18+), or IE (11+).
New API to understand
Not a lot of information available yet on best practices or case studies
Learn more:
I wrote a little snippet to compare using MutationObserers to handling a variety of events. I used balupton's code since his answer has the most upvotes.
Mozilla has an excellent page on the API
Take a look at the MutationSummary library
non jQuery quick and dirty answer:
function setChangeListener (div, listener) {
div.addEventListener("blur", listener);
div.addEventListener("keyup", listener);
div.addEventListener("paste", listener);
div.addEventListener("copy", listener);
div.addEventListener("cut", listener);
div.addEventListener("delete", listener);
div.addEventListener("mouseup", listener);
}
var div = document.querySelector("someDiv");
setChangeListener(div, function(event){
console.log(event);
});
I have modified lawwantsin 's answer like so and this works for me. I use the keyup event instead of keypress which works great.
$('#editor').on('focus', function() {
before = $(this).html();
}).on('blur keyup paste', function() {
if (before != $(this).html()) { $(this).trigger('change'); }
});
$('#editor').on('change', function() {alert('changed')});
Two options:
1) For modern (evergreen) browsers:
The "input" event would act as an alternative "change" event.
https://developer.mozilla.org/en-US/docs/Web/Events/input
document.querySelector('div').addEventListener('input', (e) => {
// Do something with the "change"-like event
});
or
<div oninput="someFunc(event)"></div>
or (with jQuery)
$('div').on('click', function(e) {
// Do something with the "change"-like event
});
2) To account for IE11 and modern (evergreen) browsers:
This watches for element changes and their contents inside the div.
https://developer.mozilla.org/en-US/docs/Web/API/MutationObserver
var div = document.querySelector('div');
var divMO = new window.MutationObserver(function(e) {
// Do something on change
});
divMO.observe(div, { childList: true, subtree: true, characterData: true });
const p = document.querySelector('p')
const result = document.querySelector('div')
const observer = new MutationObserver((mutationRecords) => {
result.textContent = mutationRecords[0].target.data
// result.textContent = p.textContent
})
observer.observe(p, {
characterData: true,
subtree: true,
})
<p contenteditable>abc</p>
<div />
Here's what worked for me:
var clicked = {}
$("[contenteditable='true']").each(function(){
var id = $(this).attr("id");
$(this).bind('focus', function() {
// store the original value of element first time it gets focus
if(!(id in clicked)){
clicked[id] = $(this).html()
}
});
});
// then once the user clicks on save
$("#save").click(function(){
for(var id in clicked){
var original = clicked[id];
var current = $("#"+id).html();
// check if value changed
if(original != current) save(id,current);
}
});
This thread was very helpful while I was investigating the subject.
I've modified some of the code available here into a jQuery plugin so it is in a re-usable form, primarily to satisfy my needs but others may appreciate a simpler interface to jumpstart using contenteditable tags.
https://gist.github.com/3410122
Update:
Due to its increasing popularity the plugin has been adopted by Makesites.org
Development will continue from here:
https://github.com/makesites/jquery-contenteditable
Non JQuery answer...
function makeEditable(elem){
elem.setAttribute('contenteditable', 'true');
elem.addEventListener('blur', function (evt) {
elem.removeAttribute('contenteditable');
elem.removeEventListener('blur', evt.target);
});
elem.focus();
}
To use it, call on (say) a header element with id="myHeader"
makeEditable(document.getElementById('myHeader'))
That element will now be editable by the user until it loses focus.
In Angular 2+
<div contentEditable (input)="type($event)">
Value
</div>
#Component({
...
})
export class ContentEditableComponent {
...
type(event) {
console.log(event.data) // <-- The pressed key
console.log(event.path[0].innerHTML) // <-- The content of the div
}
}
To avoid timers and "save" buttons, you may use blur event wich fires when the element loses focus. but to be sure that the element was actually changed (not just focused and defocused), its content should be compared against its last version. or use keydown event to set some "dirty" flag on this element.
Here is the solution I ended up using and works fabulously. I use $(this).text() instead because I am just using a one line div that is content editable. But you may also use .html() this way you dont have to worry about the scope of a global/non-global variable and the before is actually attached to the editor div.
$('body').delegate('#editor', 'focus', function(){
$(this).data('before', $(this).html());
});
$('#client_tasks').delegate('.task_text', 'blur', function(){
if($(this).data('before') != $(this).html()){
/* do your stuff here - like ajax save */
alert('I promise, I have changed!');
}
});
You need to use input event type
Demo
HTML
<div id="editor" contenteditable="true" >Some text here</div>
JS
const input = document.getElementById('editor');
input.addEventListener('input', updateValue);
function updateValue(e) {
console.log(e.target);
}
know more
The onchange event doesn't fires when an element with the contentEditable attribute is changed, a suggested approach could be to add a button, to "save" the edition.
Check this plugin which handles the issue in that way:
Creating a quick and dirty jQuery contentEditable Plugin
Using DOMCharacterDataModified under MutationEvents will lead to the same. The timeout is setup to prevent sending incorrect values (e.g. in Chrome I had some issues with space key)
var timeoutID;
$('[contenteditable]').bind('DOMCharacterDataModified', function() {
clearTimeout(timeoutID);
$that = $(this);
timeoutID = setTimeout(function() {
$that.trigger('change')
}, 50)
});
$('[contentEditable]').bind('change', function() {
console.log($(this).text());
})
JSFIDDLE example
I built a jQuery plugin to do this.
(function ($) {
$.fn.wysiwygEvt = function () {
return this.each(function () {
var $this = $(this);
var htmlold = $this.html();
$this.bind('blur keyup paste copy cut mouseup', function () {
var htmlnew = $this.html();
if (htmlold !== htmlnew) {
$this.trigger('change')
}
})
})
}
})(jQuery);
You can simply call $('.wysiwyg').wysiwygEvt();
You can also remove / add events if you wish
A simple answer in JQuery, I just created this code and thought it will be helpful for others too
var cont;
$("div [contenteditable=true]").focus(function() {
cont=$(this).html();
});
$("div [contenteditable=true]").blur(function() {
if ($(this).html()!=cont) {
//Here you can write the code to run when the content change
}
});
For me, I want to check the input is valid or not.
If valid, then update, Otherwise show an error message and keep the value as same as before.
Skill: When you edit done, usually, it will trigger the blur event.
Example
<span contenteditable="true">try input somethings.</span>
<script>
const elem = document.querySelector(`span`)
let oldValue = elem.innerText
elem.onkeydown = (keyboardEvent) => {
if (keyboardEvent.key === "Enter") {
elem.blur() // set focusout
}
}
elem.onblur = (e) => {
const curValue = elem.innerText
if (curValue === oldValue) {
return
}
if (curValue.length <= 50) { // 👈 Input your conditions.
// 👇 fail
elem.innerText = oldValue
// (Optional) Add error message
elem.insertAdjacentHTML("beforeend", `<span style="margin-left:5px;color:red">error length=${curValue.length}. Must greater than 50. undo to the previous value.</span>`)
const errMsg = elem.querySelector(`span`)
setTimeout(() => errMsg.remove(), 3500) // wait 3.5 second, and then remove it.
return
}
// 👇 OK, update
oldValue = curValue
}
</script>
Check this idea out.
http://pastie.org/1096892
I think it's close. HTML 5 really needs to add the change event to the spec. The only problem is that the callback function evaluates if (before == $(this).html()) before the content is actually updated in $(this).html(). setTimeout don't work, and it's sad. Let me know what you think.
Based on #balupton's answer:
$(document).on('focus', '[contenteditable]', e => {
const self = $(e.target)
self.data('before', self.html())
})
$(document).on('blur', '[contenteditable]', e => {
const self = $(e.target)
if (self.data('before') !== self.html()) {
self.trigger('change')
}
})
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>

Javascript: get element ID from event

How to get the ID of an element passed as (e)?
window.addEventListener('load', function(){
var tags = document.getElementsByClassName("tag");
for (i=0; i<tags.length; i++){
tags[i].addEventListener('mousedown', function(e){ tagClick(e) }, false);
}
}, false);
function tagClick(e){
/* here I'm gonna need the event to cancel the bubble and the ID to work with it*/
alert('The id of the element you clicked: ' + [?object].id);
[?object].className='newClass';
e.stopPropagation();
e.cancelBubble = true;
}
I need to get the element/object inside tagClick so I can change its properties
html:
<div class="tag">
<img src="/images/tags/sample.jpg"/>
<label class="tagLabel">Sample</label>
</div>
See, the element with the event attached is the div, but ig gives me the image object instead when using e.srcElement.
When you bind an event listener with addEventListener, it's called with this referring to the element you bound the event on. So this.id will be the id of the element (if it has one).
alert('The id of the element you clicked: ' + this.id);
But you're breaking that with this line:
tags[i].addEventListener('mousedown', function(e){ tagClick(e) }, false);
...because you're putting an extra function in the middle, then calling tagClick without setting this. There's no need for that extra function, change that to:
tags[i].addEventListener('mousedown', tagClick, false);
...so this doesn't get messed up. Or alternately if you prefer to have the extra function, ensure this is maintained using Function#call:
tags[i].addEventListener('mousedown', function(e){ tagClick.call(this, e) }, false);
...but there's no reason to do that with the tagClick function shown.
The (standard) event object also has the properties target (which may not be the element you bound the event on, it may well be a descendant) and currentTarget (which will be the element you bound the event on). But this is convenient and reliable if you use addEventListener (or even attachEvent, on IE).
You can get the target of the event with e.target.
However keep in mind that some browsers consider text nodes to be a target, so try something like this:
var t = e.target;
while(t && !t.id) t = t.parentNode;
if( t) {
alert("You clicked element #"+t.id);
}
This will find the first element that actually has an ID.
Happy New Year!
EDIT: On second thought, if it's the "tag" element itself you want to refer to, just use this. In an event handler, this refers to the element that actually has the handler. Although in this case you'll need to change your handler to ('mousedown', tagClick, false)
Or better still:
document.body.addEventListener("mousedown",function(e) {
var t = e.target;
while(t && t.nodeName != "TAG") { // note, must be uppercase
t = t.parentNode;
}
if( t) {
alert("You clicked on #"+t.id);
}
},false);
Fewer event handlers is always better.
document.getElementById("body").addEventListener("mousedown", function(e){
console.log(e.target.id);
});
enjoy.

jQuery form on ready/load does not work

I have this 'template' code (just for example):
$(document).on("<EVENT>", "form", function() {
$(this).find(".input input").each(function() {
var required = $(this).attr("required");
var checkField = $(this).closest("tr").children(".check");
var errorField = $(this).closest("tr").children(".errormessage");
if (required != undefined) {
$(checkField).css("color", "#FFFF00");
$(checkField).html("✘");
$(errorField).css("color", "#FFFF00");
$(errorField).html("(Required)");
}
else {
$(checkField).css("color", "#FFFF00");
$(checkField).html("✔");
$(errorField).css("color", "#000000");
$(errorField).html("");
}
});
});
When <EVENT> is for example click or mouseover, it just works as expected.
However it refuses to work on an ready or load event, any clue why?
From http://api.jquery.com/on/
In all browsers, the load, scroll, and error events (e.g., on an element) do not bubble. In Internet Explorer 8 and lower, the paste and reset events do not bubble. Such events are not supported for use with delegation, but they can be used when the event handler is directly attached to the element generating the event.

How can I attach event to a tag which is in string form?

I'm creating html on runtime like this:
var myVar = "<div id='abc'>some clickable text</div>"
Now, I want to attach some event, say onclick, to this div. How can I do that on next line? I'll add this to DOM later.
PS: I've to accomplish this without using JQuery.
Instead of building your div as a string, you'll want to use document.createElement('div'). This way you will have a real dom object, and can get and set it's propeties, including onClick
Will this help? Since you dynamically generate it, you know the control id of the DIV.
document.getElementbyId('abc').onClick = foo;
function foo()
{
alert("All your impl to go here");
}
Try building the div as a DOM element first.
var myVar = document.createElement("div"),
parentDiv = document.getElementById("parent_div");
parentDiv.appendChild(myVar);
myVar.innerHTML = "some clickable text";
if(myVar.addEventListener){
myVar.addEventListener("click", clickFn, false);
}
else if(myVar.attachEvent){
myVar.attachEvent("onclick", clickFn);
}
else{
myVar.onclick = clickFn;
}
The addEventListener method is standard, but not every browser plays nice with the standard.
EDIT: As mentioned, an element must be added to the DOM first.
Or you can use this technique: attach event to the document.body. Then if the event target is not the needed div than just do nothing. It is the same techinque jquery uses for its live function:
// crossbrowser event attachment function
function listen(evnt, elem, func) {
if (elem.addEventListener) {
elem.addEventListener(evnt, func, false);
}
else if (elem.attachEvent) {
var r = elem.attachEvent("on" + evnt, func);
return r;
}
else window.alert('I\'m sorry Dave, I\'m afraid I can\'t do that.');
}
// this is an analog of the jquery.live
var assignLiveEvent = function(id, evnt, callback) {
var handler = function(e) {
e = e || window.event;
e.target = e.target || e.srcElement;
if (e.target.id == id) {
//your code here
callback(e);
}
};
listen(evnt, document.body, handler);
};
var myVar = "<div id='abc'>some clickable text</div>";
assignLiveEvent("abc", "click", function(e) {
//your code here
});
// now you can add your div to DOM even after event handler assignation
Here is demo.
Brian Glaz is totally right but, if for some reason, you really need to do it this way, you have two options:
you can only add events to something that is already in the DOM, using pure javascript, so you would have to include it in the html like:
document.body.innerHTML += myVar;
and then, attach the event with
document.getElementById('abc').addEventListener('click', function(e){
//your code
}, 1);
With jQuery, you could use .live() to attach events to elements that are not yet present in the DOM:
$('#abc').live('click', function(e){
//your code here
});
so you could add the div later...

Attaching properties to bubbled event object in Javascript

In Chrome/Firefox I can attach my custom properties to an event object in one handler and read them in a different handler for the same event even if the event handling is bubbled up.
I cannot do the same in IE. My custom property is lost while event is bubbled up.
Do you know if there's any solution or workaround to this?
The following is an example of that problem:
<div id="div1">
<input type="button" value="Foo" id="button1">
</div>
<script>
function attach(el, event, fn) {
if (el.addEventListener) {
el.addEventListener(event, fn);
} else if (el.attachEvent) {
el.attachEvent('on'+event, fn);
}
}
attach(document.getElementById("button1"), 'click', function (event) {
event.abc = "done";
return true;
});
attach(document.getElementById("div1"), 'click', function (event) {
alert(event.abc);
return true;
});
</script>
According with my test you cannot add property to event object in IE (IE8 tested).
Try next code:
attach(document.getElementById("button1"), 'click', function (ev) {
//ev=ev||event;
//ev.abc = "done";
// next lines show you why you cannot save properties in event object
var xx1=event;
var xx2=event;
alert(xx1===xx2); // // showed *false* in IE8, but expected *true*
return true;
});
I am not sure but maybe, when event object is requested, IE8 always return new object, that contains same properties/values as previous requested.

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