Moving strings and triggering events with jquery

Moving strings and triggering events with jquery - javascript

So this follows along with some similar questions that have been asked on here but mine is a very specific scenario I'm trying to work within. The situation is I'm on the production end of a CMS and I need to manipulate a forms module in a very specific way but my current access is very limited. In plain english, I need to be able to click a button, have that click append a specific string into a text field and then trigger the click event on another button after this string has been appended. What I have so far, while not perfect, seems like it should work but is not. And yes I'm aware that this is a very odd, roundabout way of doing this but it's a short-term hotfix to accommodate a deadline so trust me when I say this approach is the only current option.
The code:
CSS:
<style>
.form-group {
visibility: hidden;
}
input[type="submit"] {
visibility: hidden;
}
</style>
Js:
<script>
$("#yes").click(function(){
$('#yesHide').contents().appendTo('#textFieldID');
$('#submitID').trigger('click');
});
$("#no").click(function(){
$('#noHide').contents().appendTo('#textFieldID');
$('#submitID').trigger('click');
});
</script>
HTML:
<a id="yes">yes</a>
<a id="no">no</a>
<p id="yesHide" style="visibility: hidden;">This page was helpful</p>
<p id="noHide" style="visibility: hidden;">This page was not helpful</p>

If the button lives in a form, you can try triggering the submit on the form like this:
$('#formID').trigger('submit');
Otherwise, you'll need an event handler on your #submitID button that actually does something, otherwise you'll be triggering an event that isn't being listened for.

Related

Dynamic Jquery On Focus

I have a situation similar to this one where I have a button that I need to have no pointer events AND show a not-allowed cursor.
The answer given by #Petr Odut worked spectacularly (many thanks) except for the part about the tab index and on focus.
The solution he gave to that problem involves hard coding the tab index and on focus attributes into the specific element. However my element has its disabled class added programmatically with jQuery. Sometimes it is disabled, sometimes it isn't, so I cannot hard code those attributes.
I know I could set those attributes with jQuery at the same time I set the disabled class, but this button is not the only button I'd like to have this functionality for. I'd like some way to set the tab index/on focus globally, so that any disabled button exhibits that behavior.
So, is there a way to do that?
Note: I'm still new on stackoverflow and don't have enough reputation to ask this question directly in a comment on the post, which is why I am doing this. I apologize if asking this way is improper etiquette.
Also, much thanks Petr.

Something like this?
and pure JS version:
[...document.querySelectorAll('a.disabled')].forEach(a => {
a.setAttribute("tabindex", "-1");
a.setAttribute("onfocus", "this.blur()");
console.log(a.getAttribute("tabindex"));
})
$("a.disabled").each(function(i) {
$(this).attr('tabindex', "-1").attr('onfocus', "this.blur()");
console.log($(this).attr('tabindex'))
});
/* Adding cursor just works: */
.disabled {
cursor: not-allowed;
}
/* Makes link non-clickable: */
.disabled:active {
pointer-events: none;
}
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
Disabled link
Disabled link2
NOT Disabled link3

Making a button a clickable link (With a twist)

So I have a snippet that I'm using to build some buttons.
<font color=white><button class="button"><span>Register</span></button></font>
<button class="button" onclick="window.location='http://www.google.com';"><span>SP Training</span></button>
<button class="button"><span>Assistance</span></button>
<button class="button"><span>Orders</span></button>
<button class="button"><span>KM Milsuite</span></button>
<button class="button"><span>TMT</span></button>
As you can see I have tried wrapping the whole thing in href, I have tried wrapping the span in href, I have tried wrapping just the font in href, all failed
Ok so I trekked down the java world and tried some on click (numerous variations I have found on this site) none of which work! Every button is a clickable but EVERY button simply links back to the page i'm currently working on. By no means am I an expert at all this but I expected a little give on this!
Any suggestions?

The purpose of a button is to either:
Submit a form (type="submit", the default)
Allow JavaScript to be triggered (type="button")
As you can see I have tried wrapping the whole thing in href
The HTML specification forbids that.
I have tried wrapping the span in href
The span appears to serve no purpose
Every button is a clickable but EVERY button simply links back to the page i'm currently working on
If clicking the button is reloading the current page, then it is probably a submit button inside a form with an action attribute that resolves to the current page (or no action attribute).
If you want a link then use a link and do not use a button.
If you want your link to look like a button, then use CSS to style it that way. Note that the :active pseudo-class is useful for achieving the 3d depressed effect when the link is clicked.

The span tag inside your button is catching the click action. You must take the span out of the "bubbling" chain.
The easiest way is to apply CSS and add the class to your span tags.
span.nonclickable {
pointer-events: none;
}
After that you can catch the button clicks.
A more detailed explanation can be found here: Use CSS to make a span not clickable
It is not quite clear what you want these buttons to do. Use a-tags to link to other pages and use buttons to refer to an action in javascript or a form submit.

You could try this :
<input type="button" onclick="myF()" />
<script>
function myF() {
window.open('http://www.google.com', '_blank', 'resizable=yes');
}
</script>
Hope it helps

url link as on and off button without following url [duplicate]

The following are two methods of building a link that has the sole purpose of running JavaScript code. Which is better, in terms of functionality, page load speed, validation purposes, etc.?
function myJsFunc() {
alert("myJsFunc");
}
Run JavaScript Code
or
function myJsFunc() {
alert("myJsFunc");
}
Run JavaScript Code

I use javascript:void(0).
Three reasons. Encouraging the use of # amongst a team of developers inevitably leads to some using the return value of the function called like this:
function doSomething() {
//Some code
return false;
}
But then they forget to use return doSomething() in the onclick and just use doSomething().
A second reason for avoiding # is that the final return false; will not execute if the called function throws an error. Hence the developers have to also remember to handle any error appropriately in the called function.
A third reason is that there are cases where the onclick event property is assigned dynamically. I prefer to be able to call a function or assign it dynamically without having to code the function specifically for one method of attachment or another. Hence my onclick (or on anything) in HTML markup look like this:
onclick="someFunc.call(this)"
OR
onclick="someFunc.apply(this, arguments)"
Using javascript:void(0) avoids all of the above headaches, and I haven't found any examples of a downside.
So if you're a lone developer then you can clearly make your own choice, but if you work as a team you have to either state:
Use href="#", make sure onclick always contains return false; at the end, that any called function does not throw an error and if you attach a function dynamically to the onclick property make sure that as well as not throwing an error it returns false.
OR
Use href="javascript:void(0)"
The second is clearly much easier to communicate.

Neither.
If you can have an actual URL that makes sense use that as the HREF. The onclick won't fire if someone middle-clicks on your link to open a new tab or if they have JavaScript disabled.
If that is not possible, then you should at least inject the anchor tag into the document with JavaScript and the appropriate click event handlers.
I realize this isn't always possible, but in my opinion it should be striven for in developing any public website.
Check out Unobtrusive JavaScript and Progressive enhancement (both Wikipedia).

Doing Link or Link or whatever else that contains an onclick attribute - was okay back five years ago, though now it can be a bad practice. Here's why:
It promotes the practice of obtrusive JavaScript - which has turned out to be difficult to maintain and difficult to scale. More on this in Unobtrusive JavaScript.
You're spending your time writing incredibly overly verbose code - which has very little (if any) benefit to your codebase.
There are now better, easier, and more maintainable and scalable ways of accomplishing the desired result.
The unobtrusive JavaScript way
Just don't have a href attribute at all! Any good CSS reset would take care of the missing default cursor style, so that is a non-issue. Then attach your JavaScript functionality using graceful and unobtrusive best practices - which are more maintainable as your JavaScript logic stays in JavaScript, instead of in your markup - which is essential when you start developing large scale JavaScript applications which require your logic to be split up into blackboxed components and templates. More on this in Large-scale JavaScript Application Architecture
Simple code example
// Cancel click event
$('.cancel-action').click(function(){
alert('Cancel action occurs!');
});
// Hover shim for Internet Explorer 6 and Internet Explorer 7.
$(document.body).on('hover','a',function(){
$(this).toggleClass('hover');
});
a { cursor: pointer; color: blue; }
a:hover,a.hover { text-decoration: underline; }
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<a class="cancel-action">Cancel this action</a>
A blackboxed Backbone.js example
For a scalable, blackboxed, Backbone.js component example - see this working jsfiddle example here. Notice how we utilize unobtrusive JavaScript practices, and in a tiny amount of code have a component that can be repeated across the page multiple times without side-effects or conflicts between the different component instances. Amazing!
Notes
Omitting the href attribute on the a element will cause the element to not be accessible using tab key navigation. If you wish for those elements to be accessible via the tab key, you can set the tabindex attribute, or use button elements instead. You can easily style button elements to look like normal links as mentioned in Tracker1's answer.
Omitting the href attribute on the a element will cause Internet Explorer 6 and Internet Explorer 7 to not take on the a:hover styling, which is why we have added a simple JavaScript shim to accomplish this via a.hover instead. Which is perfectly okay, as if you don't have a href attribute and no graceful degradation then your link won't work anyway - and you'll have bigger issues to worry about.
If you want your action to still work with JavaScript disabled, then using an a element with a href attribute that goes to some URL that will perform the action manually instead of via an Ajax request or whatever should be the way to go. If you are doing this, then you want to ensure you do an event.preventDefault() on your click call to make sure when the button is clicked it does not follow the link. This option is called graceful degradation.

'#' will take the user back to the top of the page, so I usually go with void(0).
javascript:; also behaves like javascript:void(0);

I would honestly suggest neither. I would use a stylized <button></button> for that behavior.
button.link {
display: inline-block;
position: relative;
background-color: transparent;
cursor: pointer;
border: 0;
padding: 0;
color: #00f;
text-decoration: underline;
font: inherit;
}
<p>A button that looks like a <button type="button" class="link">link</button>.</p>
This way you can assign your onclick. I also suggest binding via script, not using the onclick attribute on the element tag. The only gotcha is the psuedo 3d text effect in older IEs that cannot be disabled.
If you MUST use an A element, use javascript:void(0); for reasons already mentioned.
Will always intercept in case your onclick event fails.
Will not have errant load calls happen, or trigger other events based on a hash change
The hash tag can cause unexpected behavior if the click falls through (onclick throws), avoid it unless it's an appropriate fall-through behavior, and you want to change the navigation history.
NOTE: You can replace the 0 with a string such as javascript:void('Delete record 123') which can serve as an extra indicator that will show what the click will actually do.

The first one, ideally with a real link to follow in case the user has JavaScript disabled. Just make sure to return false to prevent the click event from firing if the JavaScript executes.
Link
If you use Angular2, this way works:
<a [routerLink]="" (click)="passTheSalt()">Click me</a>.
See here https://stackoverflow.com/a/45465728/2803344

Neither if you ask me;
If your "link" has the sole purpose of running some JavaScript code it doesn't qualify as a link; rather a piece of text with a JavaScript function coupled to it. I would recommend to use a <span> tag with an onclick handler attached to it and some basic CSS to immitate a link. Links are made for navigation, and if your JavaScript code isn't for navigation it should not be an <a> tag.
Example:
function callFunction() { console.log("function called"); }
.jsAction {
cursor: pointer;
color: #00f;
text-decoration: underline;
}
<p>I want to call a JavaScript function <span class="jsAction" onclick="callFunction();">here</span>.</p>

Ideally you'd do this:
Link text
Or, even better, you'd have the default action link in the HTML, and you'd add the onclick event to the element unobtrusively via JavaScript after the DOM renders, thus ensuring that if JavaScript is not present/utilized you don't have useless event handlers riddling your code and potentially obfuscating (or at least distracting from) your actual content.

Using just # makes some funny movements, so I would recommend to use #self if you would like to save on typing efforts of JavaScript bla, bla,.

I use the following
Link
instead
Link

I recommend using a <button> element instead, especially if the control is supposed to produce a change in the data. (Something like a POST.)
It's even better if you inject the elements unobtrusively, a type of progressive enhancement. (See this comment.)

I agree with suggestions elsewhere stating that you should use regular URL in href attribute, then call some JavaScript function in onclick. The flaw is, that they automaticaly add return false after the call.
The problem with this approach is, that if the function will not work or if there will be any problem, the link will become unclickable. Onclick event will always return false, so the normal URL will not be called.
There's very simple solution. Let function return true if it works correctly. Then use the returned value to determine if the click should be cancelled or not:
JavaScript
function doSomething() {
alert( 'you clicked on the link' );
return true;
}
HTML
link text
Note, that I negate the result of the doSomething() function. If it works, it will return true, so it will be negated (false) and the path/to/some/URL will not be called. If the function will return false (for example, the browser doesn't support something used within the function or anything else goes wrong), it is negated to true and the path/to/some/URL is called.

# is better than javascript:anything, but the following is even better:
HTML:
For great justice
JavaScript:
$(function() {
$(".some-selector").click(myJsFunc);
});
You should always strive for graceful degradation (in the event that the user doesn't have JavaScript enabled...and when it is with specs. and budget). Also, it is considered bad form to use JavaScript attributes and protocol directly in HTML.

Unless you're writing out the link using JavaScript (so that you know it's enabled in the browser), you should ideally be providing a proper link for people who are browsing with JavaScript disabled and then prevent the default action of the link in your onclick event handler. This way those with JavaScript enabled will run the function and those with JavaScript disabled will jump to an appropriate page (or location within the same page) rather than just clicking on the link and having nothing happen.

Definitely hash (#) is better because in JavaScript it is a pseudoscheme:
pollutes history
instantiates new copy of engine
runs in global scope and doesn't respect event system.
Of course "#" with an onclick handler which prevents default action is [much] better. Moreover, a link that has the sole purpose to run JavaScript is not really "a link" unless you are sending user to some sensible anchor on the page (just # will send to top) when something goes wrong. You can simply simulate look and feel of link with stylesheet and forget about href at all.
In addition, regarding cowgod's suggestion, particularly this: ...href="javascript_required.html" onclick="... This is good approach, but it doesn't distinguish between "JavaScript disabled" and "onclick fails" scenarios.

I usually go for
Link description
It's shorter than javascript:void(0) and does the same.

I choose use javascript:void(0), because use this could prevent right click to open the content menu. But javascript:; is shorter and does the same thing.

I would use:
Link
Reasons:
This makes the href simple, search engines need it. If you use anything else ( such as a string), it may cause a 404 not found error.
When mouse hovers over the link, it doesn't show that it is a script.
By using return false;, the page doesn't jump to the top or break the back button.

Don't use links for the sole purpose of running JavaScript.
The use of href="#" scrolls the page to the top; the use of void(0) creates navigational problems within the browser.
Instead, use an element other than a link:
<span onclick="myJsFunc()" class="funcActuator">myJsFunc</span>
And style it with CSS:
.funcActuator {
cursor: default;
}
.funcActuator:hover {
color: #900;
}

So, when you are doing some JavaScript things with an <a /> tag and if you put href="#" as well, you can add return false at the end of the event (in case of inline event binding) like:
Run JavaScript Code
Or you can change the href attribute with JavaScript like:
Run JavaScript Code
or
Run JavaScript Code
But semantically, all the above ways to achieve this are wrong (it works fine though). If any element is not created to navigate the page and that have some JavaScript things associated with it, then it should not be a <a> tag.
You can simply use a <button /> instead to do things or any other element like b, span or whatever fits there as per your need, because you are allowed to add events on all the elements.
So, there is one benefit to use <a href="#">. You get the cursor pointer by default on that element when you do a href="#". For that, I think you can use CSS for this like cursor:pointer; which solves this problem also.
And at the end, if you are binding the event from the JavaScript code itself, there you can do event.preventDefault() to achieve this if you are using <a> tag, but if you are not using a <a> tag for this, there you get an advantage, you don't need to do this.
So, if you see, it's better not to use a tag for this kind of stuff.

It would be better to use jQuery,
$(document).ready(function() {
$("a").css("cursor", "pointer");
});
and omit both href="#" and href="javascript:void(0)".
The anchor tag markup will be like
<a onclick="hello()">Hello</a>
Simple enough!

Usually, you should always have a fall back link to make sure that clients with JavaScript disabled still has some functionality. This concept is called unobtrusive JavaScript.
Example... Let's say you have the following search link:
Search
You can always do the following:
var link = document.getElementById('searchLink');
link.onclick = function() {
try {
// Do Stuff Here
} finally {
return false;
}
};
That way, people with JavaScript disabled are directed to search.php while your viewers with JavaScript view your enhanced functionality.

If you happen to be using AngularJS, you can use the following:
Do some fancy JavaScript
Which will not do anything.
In addition
It will not take you to the top of the page, as with (#)
Therefore, you don't need to explicitly return false with JavaScript
It is short an concise

Depending on what you want to accomplish, you could forget the onclick and just use the href:
Link Text
It gets around the need to return false. I don't like the # option because, as mentioned, it will take the user to the top of the page. If you have somewhere else to send the user if they don't have JavaScript enabled (which is rare where I work, but a very good idea), then Steve's proposed method works great.
Link text
Lastly, you can use javascript:void(0) if you do not want anyone to go anywhere and if you don't want to call a JavaScript function. It works great if you have an image you want a mouseover event to happen with, but there's not anything for the user to click on.

I believe you are presenting a false dichotomy. These are not the only two options.
I agree with Mr. D4V360 who suggested that, even though you are using the anchor tag, you do not truly have an anchor here. All you have is a special section of a document that should behave slightly different. A <span> tag is far more appropriate.

I tried both in google chrome with the developer tools, and the id="#" took 0.32 seconds. While the javascript:void(0) method took only 0.18 seconds. So in google chrome, javascript:void(0) works better and faster.

I personally use them in combination. For example:
HTML
Link
with little bit of jQuery
$('a[href="#"]').attr('href','javascript:void(0);');
or
$('a[href="#"]').click(function(e) {
e.preventDefault();
});
But I'm using that just for preventing the page jumping to the top when the user clicks on an empty anchor. I'm rarely using onClick and other on events directly in HTML.
My suggestion would be to use <span> element with the class attribute instead of
an anchor. For example:
<span class="link">Link</span>
Then assign the function to .link with a script wrapped in the body and just before the </body> tag or in an external JavaScript document.
<script>
(function($) {
$('.link').click(function() {
// do something
});
})(jQuery);
</script>
*Note: For dynamically created elements, use:
$('.link').on('click', function() {
// do something
});
And for dynamically created elements which are created with dynamically created elements, use:
$(document).on('click','.link', function() {
// do something
});
Then you can style the span element to look like an anchor with a little CSS:
.link {
color: #0000ee;
text-decoration: underline;
cursor: pointer;
}
.link:active {
color: red;
}
Here's a jsFiddle example of above aforementioned.

On a modern website the use of href should be avoided if the element is only doing JavaScript functionality (not a real link).
Why?
The presence of this element tells the browser that this is a link with a destination.
With that, the browser will show the Open In New Tab / Window function (also triggered when you use shift+click).
Doing so will result in opening the same page without the desired function triggered (resulting in user frustration).
In regards to IE:
As of IE8, element styling (including hover) works if the doctype is set. Other versions of IE are not really to worry about anymore.
Only Drawback:
Removing HREF removes the tabindex.
To overcome this, you can use a button that's styled as a link or add a tabindex attribute using JS.

When I've got several faux-links, I prefer to give them a class of 'no-link'.
Then in jQuery, I add the following code:
$(function(){
$('.no-link').click(function(e){
e.preventDefault();
});
});
And for the HTML, the link is simply
Faux-Link
I don't like using Hash-Tags unless they're used for anchors, and I only do the above when I've got more than two faux-links, otherwise I go with javascript:void(0).
Faux-Link
Typically, I like to just avoid using a link at all and just wrap something around in a span and use that as a way to active some JavaScript code, like a pop-up or a content-reveal.

It's nice to have your site be accessible by users with JavaScript disabled, in which case the href points to a page that performs the same action as the JavaScript being executed. Otherwise I use "#" with a "return false;" to prevent the default action (scroll to top of the page) as others have mentioned.
Googling for "javascript:void(0)" provides a lot of information on this topic. Some of them, like this one mention reasons to NOT use void(0).

span inside button, is not clickable in Firefox

My CODE
HTML:
<p id="console"></p>
<button>Click <span class="icon"></span>
</button>
JS:
$('.icon').click(function () {
$('#console').html('Icon has been clicked');
return false;
});
$('button').click(function () {
$('#console').html('Button has been clicked');
});
CSS:
.icon {
background-position: -96px 0;
display: inline-block;
width: 14px;
height: 14px;
margin-top: 1px;
line-height: 14px;
vertical-align: text-top;
background-image: url("http://twitter.github.com/bootstrap/assets/img/glyphicons-halflings.png");
background-repeat: no-repeat;
}
Demo
Problem
I am able to click on .icon in Chrome , but not in Firefox. When I click on .icon, it clicks on whole button.
Question:
Isnt my code valid ? If my code is valid, whats the solution to this problem.
What I have tried
I have tried doing $('.icon').click() from console and it works perfectly in ff, so I guess the problem is that span is not clickable inside button.
e.preventDefault() and e.stopPropagation are not working either.
I've tried putting inside span but its not working either.

Refer to the spec, most notably the forbidden contents (in the SGML definition; for assistance reading that, look here): as, forms, form "controls" (input, select, etc), and fieldsets.
While you are correct in asserting that spans (and divs, etc) are legal contents of a button element, the illegal elements are all to do with having button content that does anything other than layout / styling.
I don't see anything in the spec precluding what you're trying to do, but I do see a lot discouraging it, and would be unsurprised if various browsers also "discouraged" that by not supporting it.
Which is to say: find another way to do what you want if you want to have cross-browser support. I don't understand what you're actually trying to do, so I don't think its possible to propose alternatives. I get that you want to respond differently to clicking on the button vs the icon -- but that's a (good, btw) demonstration of what you don't want to happen, not an explanation of an actual problem you want to solve.
One way might be to not use a button, and instead use another span or a div:
<p id="console"></p>
<div class="button_replace">Click <span class="icon"></span></div>
<script>
$('.icon').click(function () {
$('#console').html('Icon has been clicked');
return false;
});
$('.button_replace').click(function () {
$('#console').html('Button has been clicked');
});
</script>

If you're here, maybe this solution will work for you, even though it's not really related directly to the question.
If you've applied a
$("button").click() listener, and
your button contains a <span> or any other <tag>, and
your .click callback function refers to $(this) (or even this)
Then, if you click on the button, this will likely be the top-most tag you CLICKED ON.
This will often, such as in my case, misattribute the caller, causing script errors.
Hope it helps someone out there!

Using previous answers, I found that just changing my to fixed the problem and allowed me to have content inside the button.
The styling is virtually the same, I just left the same bootstrap button classes and element in there and it behaves just the same as before. The tabindex is there because I'm using a dropdown list inside the button so that the button (now div) can be focused and have (blur) or (focusout) event in Angular.

Which "href" value should I use for JavaScript links, "#" or "javascript:void(0)"?

The following are two methods of building a link that has the sole purpose of running JavaScript code. Which is better, in terms of functionality, page load speed, validation purposes, etc.?
function myJsFunc() {
alert("myJsFunc");
}
Run JavaScript Code
or
function myJsFunc() {
alert("myJsFunc");
}
Run JavaScript Code

I use javascript:void(0).
Three reasons. Encouraging the use of # amongst a team of developers inevitably leads to some using the return value of the function called like this:
function doSomething() {
//Some code
return false;
}
But then they forget to use return doSomething() in the onclick and just use doSomething().
A second reason for avoiding # is that the final return false; will not execute if the called function throws an error. Hence the developers have to also remember to handle any error appropriately in the called function.
A third reason is that there are cases where the onclick event property is assigned dynamically. I prefer to be able to call a function or assign it dynamically without having to code the function specifically for one method of attachment or another. Hence my onclick (or on anything) in HTML markup look like this:
onclick="someFunc.call(this)"
OR
onclick="someFunc.apply(this, arguments)"
Using javascript:void(0) avoids all of the above headaches, and I haven't found any examples of a downside.
So if you're a lone developer then you can clearly make your own choice, but if you work as a team you have to either state:
Use href="#", make sure onclick always contains return false; at the end, that any called function does not throw an error and if you attach a function dynamically to the onclick property make sure that as well as not throwing an error it returns false.
OR
Use href="javascript:void(0)"
The second is clearly much easier to communicate.

Neither.
If you can have an actual URL that makes sense use that as the HREF. The onclick won't fire if someone middle-clicks on your link to open a new tab or if they have JavaScript disabled.
If that is not possible, then you should at least inject the anchor tag into the document with JavaScript and the appropriate click event handlers.
I realize this isn't always possible, but in my opinion it should be striven for in developing any public website.
Check out Unobtrusive JavaScript and Progressive enhancement (both Wikipedia).

'#' will take the user back to the top of the page, so I usually go with void(0).
javascript:; also behaves like javascript:void(0);

I would honestly suggest neither. I would use a stylized <button></button> for that behavior.
button.link {
display: inline-block;
position: relative;
background-color: transparent;
cursor: pointer;
border: 0;
padding: 0;
color: #00f;
text-decoration: underline;
font: inherit;
}
<p>A button that looks like a <button type="button" class="link">link</button>.</p>
This way you can assign your onclick. I also suggest binding via script, not using the onclick attribute on the element tag. The only gotcha is the psuedo 3d text effect in older IEs that cannot be disabled.
If you MUST use an A element, use javascript:void(0); for reasons already mentioned.
Will always intercept in case your onclick event fails.
Will not have errant load calls happen, or trigger other events based on a hash change
The hash tag can cause unexpected behavior if the click falls through (onclick throws), avoid it unless it's an appropriate fall-through behavior, and you want to change the navigation history.
NOTE: You can replace the 0 with a string such as javascript:void('Delete record 123') which can serve as an extra indicator that will show what the click will actually do.

The first one, ideally with a real link to follow in case the user has JavaScript disabled. Just make sure to return false to prevent the click event from firing if the JavaScript executes.
Link
If you use Angular2, this way works:
<a [routerLink]="" (click)="passTheSalt()">Click me</a>.
See here https://stackoverflow.com/a/45465728/2803344

Neither if you ask me;
If your "link" has the sole purpose of running some JavaScript code it doesn't qualify as a link; rather a piece of text with a JavaScript function coupled to it. I would recommend to use a <span> tag with an onclick handler attached to it and some basic CSS to immitate a link. Links are made for navigation, and if your JavaScript code isn't for navigation it should not be an <a> tag.
Example:
function callFunction() { console.log("function called"); }
.jsAction {
cursor: pointer;
color: #00f;
text-decoration: underline;
}
<p>I want to call a JavaScript function <span class="jsAction" onclick="callFunction();">here</span>.</p>

Ideally you'd do this:
Link text
Or, even better, you'd have the default action link in the HTML, and you'd add the onclick event to the element unobtrusively via JavaScript after the DOM renders, thus ensuring that if JavaScript is not present/utilized you don't have useless event handlers riddling your code and potentially obfuscating (or at least distracting from) your actual content.

Using just # makes some funny movements, so I would recommend to use #self if you would like to save on typing efforts of JavaScript bla, bla,.

I use the following
Link
instead
Link

I recommend using a <button> element instead, especially if the control is supposed to produce a change in the data. (Something like a POST.)
It's even better if you inject the elements unobtrusively, a type of progressive enhancement. (See this comment.)

I agree with suggestions elsewhere stating that you should use regular URL in href attribute, then call some JavaScript function in onclick. The flaw is, that they automaticaly add return false after the call.
The problem with this approach is, that if the function will not work or if there will be any problem, the link will become unclickable. Onclick event will always return false, so the normal URL will not be called.
There's very simple solution. Let function return true if it works correctly. Then use the returned value to determine if the click should be cancelled or not:
JavaScript
function doSomething() {
alert( 'you clicked on the link' );
return true;
}
HTML
link text
Note, that I negate the result of the doSomething() function. If it works, it will return true, so it will be negated (false) and the path/to/some/URL will not be called. If the function will return false (for example, the browser doesn't support something used within the function or anything else goes wrong), it is negated to true and the path/to/some/URL is called.

# is better than javascript:anything, but the following is even better:
HTML:
For great justice
JavaScript:
$(function() {
$(".some-selector").click(myJsFunc);
});
You should always strive for graceful degradation (in the event that the user doesn't have JavaScript enabled...and when it is with specs. and budget). Also, it is considered bad form to use JavaScript attributes and protocol directly in HTML.

Unless you're writing out the link using JavaScript (so that you know it's enabled in the browser), you should ideally be providing a proper link for people who are browsing with JavaScript disabled and then prevent the default action of the link in your onclick event handler. This way those with JavaScript enabled will run the function and those with JavaScript disabled will jump to an appropriate page (or location within the same page) rather than just clicking on the link and having nothing happen.

Definitely hash (#) is better because in JavaScript it is a pseudoscheme:
pollutes history
instantiates new copy of engine
runs in global scope and doesn't respect event system.
Of course "#" with an onclick handler which prevents default action is [much] better. Moreover, a link that has the sole purpose to run JavaScript is not really "a link" unless you are sending user to some sensible anchor on the page (just # will send to top) when something goes wrong. You can simply simulate look and feel of link with stylesheet and forget about href at all.
In addition, regarding cowgod's suggestion, particularly this: ...href="javascript_required.html" onclick="... This is good approach, but it doesn't distinguish between "JavaScript disabled" and "onclick fails" scenarios.

I usually go for
Link description
It's shorter than javascript:void(0) and does the same.

I choose use javascript:void(0), because use this could prevent right click to open the content menu. But javascript:; is shorter and does the same thing.

I would use:
Link
Reasons:
This makes the href simple, search engines need it. If you use anything else ( such as a string), it may cause a 404 not found error.
When mouse hovers over the link, it doesn't show that it is a script.
By using return false;, the page doesn't jump to the top or break the back button.

Don't use links for the sole purpose of running JavaScript.
The use of href="#" scrolls the page to the top; the use of void(0) creates navigational problems within the browser.
Instead, use an element other than a link:
<span onclick="myJsFunc()" class="funcActuator">myJsFunc</span>
And style it with CSS:
.funcActuator {
cursor: default;
}
.funcActuator:hover {
color: #900;
}

So, when you are doing some JavaScript things with an <a /> tag and if you put href="#" as well, you can add return false at the end of the event (in case of inline event binding) like:
Run JavaScript Code
Or you can change the href attribute with JavaScript like:
Run JavaScript Code
or
Run JavaScript Code
But semantically, all the above ways to achieve this are wrong (it works fine though). If any element is not created to navigate the page and that have some JavaScript things associated with it, then it should not be a <a> tag.
You can simply use a <button /> instead to do things or any other element like b, span or whatever fits there as per your need, because you are allowed to add events on all the elements.
So, there is one benefit to use <a href="#">. You get the cursor pointer by default on that element when you do a href="#". For that, I think you can use CSS for this like cursor:pointer; which solves this problem also.
And at the end, if you are binding the event from the JavaScript code itself, there you can do event.preventDefault() to achieve this if you are using <a> tag, but if you are not using a <a> tag for this, there you get an advantage, you don't need to do this.
So, if you see, it's better not to use a tag for this kind of stuff.

It would be better to use jQuery,
$(document).ready(function() {
$("a").css("cursor", "pointer");
});
and omit both href="#" and href="javascript:void(0)".
The anchor tag markup will be like
<a onclick="hello()">Hello</a>
Simple enough!

Usually, you should always have a fall back link to make sure that clients with JavaScript disabled still has some functionality. This concept is called unobtrusive JavaScript.
Example... Let's say you have the following search link:
Search
You can always do the following:
var link = document.getElementById('searchLink');
link.onclick = function() {
try {
// Do Stuff Here
} finally {
return false;
}
};
That way, people with JavaScript disabled are directed to search.php while your viewers with JavaScript view your enhanced functionality.

If you happen to be using AngularJS, you can use the following:
Do some fancy JavaScript
Which will not do anything.
In addition
It will not take you to the top of the page, as with (#)
Therefore, you don't need to explicitly return false with JavaScript
It is short an concise

Depending on what you want to accomplish, you could forget the onclick and just use the href:
Link Text
It gets around the need to return false. I don't like the # option because, as mentioned, it will take the user to the top of the page. If you have somewhere else to send the user if they don't have JavaScript enabled (which is rare where I work, but a very good idea), then Steve's proposed method works great.
Link text
Lastly, you can use javascript:void(0) if you do not want anyone to go anywhere and if you don't want to call a JavaScript function. It works great if you have an image you want a mouseover event to happen with, but there's not anything for the user to click on.

I believe you are presenting a false dichotomy. These are not the only two options.
I agree with Mr. D4V360 who suggested that, even though you are using the anchor tag, you do not truly have an anchor here. All you have is a special section of a document that should behave slightly different. A <span> tag is far more appropriate.

I tried both in google chrome with the developer tools, and the id="#" took 0.32 seconds. While the javascript:void(0) method took only 0.18 seconds. So in google chrome, javascript:void(0) works better and faster.

I personally use them in combination. For example:
HTML
Link
with little bit of jQuery
$('a[href="#"]').attr('href','javascript:void(0);');
or
$('a[href="#"]').click(function(e) {
e.preventDefault();
});
But I'm using that just for preventing the page jumping to the top when the user clicks on an empty anchor. I'm rarely using onClick and other on events directly in HTML.
My suggestion would be to use <span> element with the class attribute instead of
an anchor. For example:
<span class="link">Link</span>
Then assign the function to .link with a script wrapped in the body and just before the </body> tag or in an external JavaScript document.
<script>
(function($) {
$('.link').click(function() {
// do something
});
})(jQuery);
</script>
*Note: For dynamically created elements, use:
$('.link').on('click', function() {
// do something
});
And for dynamically created elements which are created with dynamically created elements, use:
$(document).on('click','.link', function() {
// do something
});
Then you can style the span element to look like an anchor with a little CSS:
.link {
color: #0000ee;
text-decoration: underline;
cursor: pointer;
}
.link:active {
color: red;
}
Here's a jsFiddle example of above aforementioned.

On a modern website the use of href should be avoided if the element is only doing JavaScript functionality (not a real link).
Why?
The presence of this element tells the browser that this is a link with a destination.
With that, the browser will show the Open In New Tab / Window function (also triggered when you use shift+click).
Doing so will result in opening the same page without the desired function triggered (resulting in user frustration).
In regards to IE:
As of IE8, element styling (including hover) works if the doctype is set. Other versions of IE are not really to worry about anymore.
Only Drawback:
Removing HREF removes the tabindex.
To overcome this, you can use a button that's styled as a link or add a tabindex attribute using JS.

When I've got several faux-links, I prefer to give them a class of 'no-link'.
Then in jQuery, I add the following code:
$(function(){
$('.no-link').click(function(e){
e.preventDefault();
});
});
And for the HTML, the link is simply
Faux-Link
I don't like using Hash-Tags unless they're used for anchors, and I only do the above when I've got more than two faux-links, otherwise I go with javascript:void(0).
Faux-Link
Typically, I like to just avoid using a link at all and just wrap something around in a span and use that as a way to active some JavaScript code, like a pop-up or a content-reveal.

It's nice to have your site be accessible by users with JavaScript disabled, in which case the href points to a page that performs the same action as the JavaScript being executed. Otherwise I use "#" with a "return false;" to prevent the default action (scroll to top of the page) as others have mentioned.
Googling for "javascript:void(0)" provides a lot of information on this topic. Some of them, like this one mention reasons to NOT use void(0).

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JavaScript is the programming language of the Web.