jQuery detect whether an element has been linked to - javascript

I want to attach a jQuery event handler to a <div> element such that whenever a link is clicked which points to this <div>, that handler is activated and the associated function is executed – regardless of the location of the link (same page, other page, other site) pointing to the <div> .
$("div#mydiv").on("linked_to", function(){ //is there a "linked_to" event?
//do something about it
});
Is this possible? Can scrollIntoView() be used?

What you want is quite specific and borderline undoable. I think your best bet is to detect a hash change in the URL and act accordingly.
You aren't gonna be able to detect that div#mydiv itself was clicked, but detecting the hash #mydiv comes pretty close to it.
You would use something like:
window.onhashchange = function() {
if (window.location.hash === '#mydiv') { // here you check if it was `#mydiv`
alert('hey! are you after mydiv?!')
}
}
Check an example here: http://output.jsbin.com/pikifov - click the link and notice how the hash from the URL changes.
Source for the JSBin above here.
Full code:
<div id="mydiv">mydiv</div>
<hr>
Click to go to mydiv
<script>
window.onhashchange = function() {
if (window.location.hash === '#mydiv') {
alert('hey! are you after mydiv?!')
}
}
</script>

Related

href called issue in onclick function [duplicate]

If I have this element:
Item
How can I make both href and onClick work, preferably with onClick running first?
You already have what you need, with a minor syntax change:
Item
<script type="text/javascript">
function theFunction () {
// return true or false, depending on whether you want to allow the `href` property to follow through or not
}
</script>
The default behavior of the <a> tag's onclick and href properties is to execute the onclick, then follow the href as long as the onclick doesn't return false, canceling the event (or the event hasn't been prevented)
Use jQuery. You need to capture the click event and then go on to the website.
$("#myHref").on('click', function() {
alert("inside onclick");
window.location = "http://www.google.com";
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
Click me
To achieve this use following html:
Item
<script>
function make(e) {
// ... your function code
// e.preventDefault(); // use this to NOT go to href site
}
</script>
Here is working example.
No jQuery needed.
Some people say using onclick is bad practice...
This example uses pure browser javascript. By default, it appears that the click handler will evaluate before the navigation, so you can cancel the navigation and do your own if you wish.
<a id="myButton" href="http://google.com">Click me!</a>
<script>
window.addEventListener("load", () => {
document.querySelector("#myButton").addEventListener("click", e => {
alert("Clicked!");
// Can also cancel the event and manually navigate
// e.preventDefault();
// window.location = e.target.href;
});
});
</script>
Use a <button> instead. In general, you should only use a hyperlink for navigation to a real URL.
We can style a button to look like an anchor element.
From https://developer.mozilla.org/en-US/docs/Web/HTML/Element/a#onclick_events
Anchor elements are often abused as fake buttons by setting their href to # or javascript:void(0) to prevent the page from refreshing, then listening for their click events .
These bogus href values cause unexpected behavior when copying/dragging links, opening links in a new tab/window, bookmarking, or when JavaScript is loading, errors, or is disabled. They also convey incorrect semantics to assistive technologies, like screen readers.
Use ng-click in place of onclick. and its as simple as that:
Item
<script type="text/javascript">
function theFunction () {
// return true or false, depending on whether you want to allow
// the`href` property to follow through or not
}
</script>

Can anyone think of a better way of stopping a user from clicking on anything?

Currenlty when a page is posting back or something else is going on I display a big grey div over the top of the whole page so that the user can't click the same button multiple times. This works fine 99% of the time, the other 1% is on certain mobile devices where the user can scroll/zoom away from the div.
Instead of trying to perfect the CSS so that it works correctly (this will be an on going battle with new devices) I've decided to just stop the user from being able to click anything. Something like $('a').click(function(e){e.preventDefault();}); would stop people from clicking anchor tags and navigating to the link but it wouldn't stop an onclick event in the link from firing.
I want to try to avoid changing the page too radically (like removing every onclick attribute) since the page will eventually have to be changed back to its original state. What I would like to do is intercept clicks before the onclick event is executed but I don't think that this is possible. What I do instead is hide the clicked element on mouse down and show it on mouseup of the document, this stops the click event firing but doesn't look very nice. Can anyone think of a better solution? If not then will this work on every device/browser?
var catchClickHandler = function(){
var $this = $(this);
$this.attr('data-orig-display', $this.css('display'));
$this.css({display:'none'});
};
var resetClickedElems = function(){
$('[data-orig-display]').each(function(){
$(this).css({display:$(this).attr('data-orig-display')}).removeAttr('data-orig-display');
});
};
$('#btn').click(function(){
$('a,input').on('mousedown',catchClickHandler);
$(document).on('mouseup', resetClickedElems);
setTimeout(function(){
$('a,input').off('mousedown',catchClickHandler);
$(document).off('mouseup', resetClickedElems);
}, 5000);
});
JSFiddle: http://jsfiddle.net/d4wzK/2/
You could use the jQuery BlockUI Plugin
http://www.malsup.com/jquery/block/
You can do something like this to prevent all actions of the anchor tags:
jQuery('#btn').click(function(){
jQuery('a').each(function() {
jQuery(this).attr('stopClick', jQuery(this).attr('onclick'))
.removeAttr('onclick')
.click(function(e) {
e.preventDefault();
});
});
});
That renames the onclick to stopclick if you need to revert later and also stops the default behavior of following the href.
document.addListener('click',function(e){e.preventDefault()})
Modified-
Its your duty to remove the click event from the document after you are done accomplishing with your task.
Eg -
function prevent(e){
e.preventDefault()
}
//add
document.addListener('click',prevent)
//remove
document.removeListener('click',prevent)

Automatically update javascript elements when internal Anchor/Hash is clicked

I would like to display the updated Anchor/Hash in id="demo" when a link is clicked. The layout of the document is as follows.
<html>
<head>
<script type="text/javascript">
function myfunction()
{
document.getElementById("demo").innerHTML=location.hash;
}
</script>
</head>
<body>
<h1>Javascript</h1>
<p id="demo">This is a paragraph.</p>
here
</body>
</html>
Only problem is when the link is clicked the javascript does not get the updated Anchor/Hash until the link is pressed for a second time.
It is because the location hasn't changed at this time. Here is a way you can use:
function myfunction() {
// Sets the event handler once you click, so it will execute when
// the hash will change.
window.onhashchange = function() {
document.getElementById("demo").innerHTML=location.hash;
};
}
A modern way would be:
var hashchange;
function myfunction() {
if ( !hashchange ) {
hashchange = addEventListener( 'change', function() {
document.getElementById("demo").textContent = location.hash;
// If you want to remove the event listener right after,
// you can do this:
removeEventListener( hashchange );
}, false );
}
}
Try this JQuery plugin for detecting the hash change:
http://benalman.com/code/projects/jquery-hashchange/examples/hashchange/
It's open-source, so check out the code, which is surprisingly complex-- 300+ lines (annotated, but still).
Try this:
function myfunction() {
setTimeout(function() {
document.getElementById("demo").innerHTML=location.hash;
}, 1);
}
because when you click in the link the hash is still your prevous one so you need a delay.
It is because "location" refers to an anchor WITHIN the page.
The first click, you have no location within the page, but the anchor takes you to #example, but all this happens after the onclick has done its business. The second click we have a location of #example.
See the W3 Schools documentation here.
The onclick event is fired before the anchor has had chance to do its job. This is crucial to being able to cancel the propagation of the event and prevent redirection etc. but sadly knobbles your code.

Anchor "javascript:void(0)" causing window.onbeforeunload to fire on IE

I am using a drop down widget called Chosen which has an anchor with a href javascript:void(0). When I click on the drop down it works but on IE it fires a new onbeforeunload event which is frustrating because the application confirms if you want to leave. And obviously you don't want to have those questions when you are inputting form data.
Is there a way to get rid of this problem without altering Chosen library?
Unfortunately this:
window.onbeforeunload = function (e) {
console.log(window.location);
};
Does not log javascript:void(0) either, so, I can't use it to check the target URL.
This behavior occurs in IE9 at least, and that's what I'm concerned (not the older IEs).
The only solution I can see is to add returning of false to the onclick event handler of the links. It will tell IE that you're not planning to change the page by clicking on the link.
Link
The same can be written this way:
<script>
function doSomething() {
// do Something
return false;
}
</script>
Link
I ended up listening to click events against the anchor and cancel the event to prevent onBeforeUnload from firing:
$chosen.find('.chzn-single').click(function() {
return false;
});
I know that this is pretty old...But I have come across this recently for my work. We are unfortunately still forced to support IE9. We are using Angular.js on this project that will dynamically load new content onto a page when the user clicks on an anchor tag with a data-ng-click.
In your example all you would have to do is pass the event and within the function prevent the default action and stop it from bubbling up. To do this all you would have to do is this:
// Inside the HTML
{...}
Link
{...}
<script>
function doSomething(evt) {
evt.preventDefault();
evt.stopPropagation();
// Do Something
};
</script>
{...}
In Angular all I did was the following:
// Inside the View
Add Stuff
// Inside the controller
function addStuff($event) {
$event.preventDefault();
$event.stopPropagation();
// Do Something
};
I hope that this isn't too late and I hope that it helps others.
Had the same problem. Just found your question. My solution is, you need to add onclick attribute to every chosen dropdown list anchor tag and call window.onbeforeunload = null
In my case, I've put
$(".chzn-single").attr("onclick", "window.onbeforeunload = null;");
After setting up chosen library and it works fine
don't use href's for this. A simple solution with minimal extra work:
i prefer to use a CSS class that simulates an href, obviously you will change the color and styling of this class to fit your website, but for this purposes, it's the standard blue underlined link
<style>
.linkSimulate
{
cursor: pointer;
COLOR: blue;
text-decoration: underline;
}
</style>
then use a simple anchor
<a onclick = "do_save();" class ="linkSimulate">Link</a>
Even if this question is old, i've anhanced the answer of #Bartosz, fixing the issue in the comment of #Oiva Eskola:
Wouldn't this prevent the window.onbeforeunload from working after clicking a chosen link element? – var thisOnClick;
Below is my solution to properly create the HTML onclick property, to not override or cancel the event:
var thisOnClick;
$.each( $(' .container a '), function(){
thisOnClick = $(this).attr('onclick');
if ( typeof thisOnClick == 'undefined' ) {
$(this).attr('onclick', 'window.onbeforeunload = null;');
} else if ( typeof thisOnClick == 'string' && thisOnClick.indexOf('window.onbeforeunload') == -1 ) {
$(this).attr('onclick', thisOnClick + 'window.onbeforeunload = null;');
}
});

Why does clicking a link go to the top of the page?

This may sound a weird question,
I have a page which has a link:
<a href="#" class="emails" > Email to Friends </a>
Now I have an event attach to the anchor tag so that on click the given div toggle it state.
The Javascript Code look like this:
$(document).ready(function() {
$(".emails").bind("click",function() {
$("div#container").toggle
})
})
Now the above code and all of it works fine,
but here the big deal,
when I click the given link the my focus of the page move to top of the page,
and I have to scroll all the way down to see the change.
Can anyone help me on this?
It does this because the href="#" is an empty anchor. Anchors are used for linking to specific spots within a page. An empty anchor results in the page going back to the top.
To fix this in your javascript, you need to prevent the click event from propagating or "bubbling" up the DOM. You can do this by returning false from your click event.
$(document).ready(function() {
$(".emails").bind("click",function() {
$("div#container").toggle();
return false; // prevent propagation
})
});
You can also make the event available in the bind's click handler function by using an argument, usually named e. Having access to the event allows you to call methods on it such as .preventDefault().
$(document).ready(function() {
$(".emails").bind("click", function(event) {
$("div#container").toggle();
event.preventDefault(); // this can also go at the start of the method if you prefer
})
});
This will solve all cases where anchor is empty.
$(document).ready(function () {
$('a').click(function () {
$('[href = #]');
return false;
});
});
This comes from the href='#' in the a. Just remove this tag. But then it's technically not a link any more, so the cursor will default to a text-selector when over it. You can override this using cursor:pointer in your CSS. See the left menu on this website for reference.
Use:
<a href="javascript:void(0)" class="emails" > Email to Friends </a>
Or, using jQuery,
$(document).ready(function() {
$(".emails").attr("href","javascript:void(0)");
})
Void(0) returns a.. well.. it doesn't return anything. The browser knows how to go to nothing (i.e., what would happen if you did href=""), and to # (# is the top of the page), but not how to go to a void "value".
Whenever you put a javascript: in an attribute, the attribute's value gets set to the return value of the code inside. The code is called the first time the attribute is accessed.
But, void(0) returns nothing. Not even "". The browser takes this to meant that the link is not a link at all.

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