Related
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(){
$('.no-link').click(function(e){
e.preventDefault();
});
});
And for the HTML, the link is simply
Faux-Link
I don't like using Hash-Tags unless they're used for anchors, and I only do the above when I've got more than two faux-links, otherwise I go with javascript:void(0).
Faux-Link
Typically, I like to just avoid using a link at all and just wrap something around in a span and use that as a way to active some JavaScript code, like a pop-up or a content-reveal.
It's nice to have your site be accessible by users with JavaScript disabled, in which case the href points to a page that performs the same action as the JavaScript being executed. Otherwise I use "#" with a "return false;" to prevent the default action (scroll to top of the page) as others have mentioned.
Googling for "javascript:void(0)" provides a lot of information on this topic. Some of them, like this one mention reasons to NOT use void(0).
I'm currently using a small jQuery script, included infra, to make lists with the class collapsible-list collapsible/expandable. By default, the script collapses the list (and a bit of CSS, also included infra, makes this easily noticeable for visitors) and then expands it when a visitor clicks on expandable elements.
Here are the scripts:
The jQuery
jQuery(function($) {
function prepareList() {
$('.collapsible-list').find('li:has(ul)')
.click( function(event) {
if (this == event.target) {
$(this).toggleClass('collapsible-list-expanded');
$(this).children('ul').toggle('medium');
}
return false;
})
.addClass('collapsible-list-collapsed')
.children('ul').hide();
};
$(document).ready( function() {
prepareList()
});
});
The CSS
/* Collapsible Lists */
.collapsible-list, .collapsible-list ul, .collapsible-list li {
list-style: none;
}
.collapsible-list .collapsible-list-collapsed:before {
content: "+ ";
font-weight: bold;
color: #00AA00;
}
.collapsible-list .collapsible-list-expanded:before {
content: "- ";
font-weight: bold;
color: #AA0000;
}
The CSS is included for the sake of completeness, it functions exactly as expected. The issue lies with the jQuery (and likely some other script on the page, which I cannot seem to isolate).
The script does collapse all but the top-level sections of any list given the collapsible-list class, but that's where the proper functionality ends. Now, the script behaves as expected in my test environment (and also in JSFiddle); however, once the script is implemented in my site, the lists collapse, expand one click, but, instead of staying expanded after being clicked (as they should), they immediately collapse again. This, quite obviously, renders the script useless once implemented, as any list on which it is invoked by the collapsible-list class is made unusable for visitors.
Here is a link to a page where it is currently implemented: http://wpmudev.docs.omnifora.com/docs/plugins/wpmu-dev-dashboard/. Now, I'm sure there is a script conflict somewhere, but I cannot seem to figure out what script is conflicting.
Additional Information
This site uses Bootstrap, which, I suspect, might be the source of the conflict.
Updates
I've narrowed down the potential conflicts, and it seems that Bootstrap may not be the culprit. Here is a JSFiddle with the list behaving as expected within two different Bootstrap panel setups (nested within panel-body and nested within panel): enter link description here.
I've now managed to get the list working except as to formatting. The jQuery conflict seems to have been caused by a slight error in the way one script was calling another, which leads to the collapsible-list.js file being loaded twice. Here's a working JSFiddle: enter link description here
It might work to add a .toggleClass('collapsible-list-collapsed'); in your click function.
After fiddling with things for a few hours, I was able to resolve the conflicts:
One of the script references was improperly formatted, and that was resulting in two calls to collapsible-list.js, which was causing the unexpected immediately-contract-upon-expansion behaviour.
The original script used just expanded and collapsed as classes, which was interacting with another set of rules and causing unexpected behaviour; the modified script uses more specific classes, which avoid such conflicts.
and then amend the CSS:
Someone had thought it wise to put padding: 0; onto ul and li elements in the theme's primary CSS file; this was, obviously, easily overridden with a more specific rule for .collapsible-list.
The result is that the page is now functioning as expected: http://wpmudev.docs.omnifora.com/docs/plugins/wpmu-dev-dashboard/.
I'm trying to figure out how to connect this line of HTML (which activates a hover pop-up) code which is being used in a PHP file, to the following jquery code. I've gotten it to work for in a single hover instance, but I plan on having multiple hovers all across the page.
HTML Code:
<a class="que" href="http://www.google.com">okok</a>
<div class="launch">test</div>
jQuery Code:
$(document).ready(function() {
$("div.launch").css({'display':'block','opacity':'0'})
$("a.que").hover(
function () {
$(this).next('.launch').animate({
opacity: 1
}, 500);
},
function () {
$(this).sibling('div').stop().animate({
opacity: 0
}, 200);
}
)
});
Thanks a ton for any help... :)
Just change your jQuery selector to match all elements you want to have that hover effect. The jQuery selector is the part of the jQuery statement that tells you what items to, well, select.
$(selectorGoesHere).takeSomeAction;
The selector matches the same format you use for the CSS, so, for example, any element with class="someClass" will be selected in jQuery with $(".someClass"). The jQuery selector can refer to multiple matching items simultaneously, so the jQuery statement used a moment ago would select every element that has that class and perform whatever action you chose.
If, for example, you wanted to use jQuery to set every div to have a red background, you would use:
$("div").css("background-color","#FF0000");
Broken down, that statement finds every div element (as specified by the selector), then applies the CSS style background-color: #FF0000 to EVERY div in the document.
http://jsfiddle.net/joycse06/hzm5p/1/ is an example of having multiple hover-over effects using your code. Just follow that link for a sample how how your already written jQuery statements are applied to multiple HTML elements.
EDIT: Based on the code below, change your jQuery to match http://jsfiddle.net/hzm5p/5/
jQuery(document).ready(function() {
jQuery("div.launch").css({'display':'block','opacity':'0'})
jQuery("a.que").hover(
function () {
jQuery(this).parent().next('.launch').animate({
opacity: 1
}, 500);
},
function () {
jQuery(this).parent().next('.launch').stop().animate({
opacity: 0
}, 200);
}
)
});
Simply add .parent() to get the the containing p element, then take the .next('.launch') element.
EDIT 2: For jQuery in Wordpress, you need to include the following line somewhere in your functions.php file:
wp_enqueue_script("jquery");
Also, it seems that the jQuery used by Wordpress is designed for "compatibility mode", which means the $ shortcut is by default unavailable. You'll need to use jQuery in place of $, unless you use some of the workarounds mentioned in http://digwp.com/2011/09/using-instead-of-jquery-in-wordpress/
EDIT 3: Test for jQuery loading with the following code:
if (jQuery) {
alert("jQuery loaded");
} else {
alert("jQuery not loaded");
}
If it's loaded, then I don't know what to tell you. If it isn't, you need to figure out why in Wordpress and get it loaded, or you'll need to re-write your code to use non-jQuery scripting.
You can just use class que to all <a> tags and launch class to all divs next to that <a> tags.
I have the following javascript code:
$('#s2 a').click(function(){
var cB = $(this);
var f = parseInt(cB.attr('data-f'));
var r = parseInt(cB.attr('data-r'));
var c = parseInt(cB.attr('data-c'));
if (pA == false && !isClickAllowed(f,r,c)) {
return false;
}
// more stuff comes here
}
This makes a link not clickable. This all works. I also want to remove the hover effect. The CSS code for this is:
.pc a:hover {
background-color: #FFF;
I thought removing the class would do it like: cB.removeClass('pc'); but this doesn't work.
Any suggestions on how to do this?
Thank you for your time
--EDIT--
Hmm I think I see why it aint working. At the top of the document I have this:
$(document).ready(function() {
setScale();
$(window).resize(setScale);
if (!('ontouchstart' in document)) {
$('body').addClass('pc');
}
more code here
This sets the .pc a:hover for all links when opened the page on a pc rather then a touch device (e.g. iPad). I need to disable this pc hover ONLY on the links are not clickable like in:
if (pA == false && !isClickAllowed(f,r,c)) {
return false;
}
Hope this helps!
cB is the anchor which isn't being references by the CSS class you indicate, the parent would have the class pc for this to work. cB.parent().removeClass('pc'); would do it.
-- EDIT --
Following the erudite comments below it would seem that cb.parents('.pc').removeClass('pc') or cb.parents().removeClass('pc') (I've not benchmarked to see which is quicker) would be the comprehensive solution.
Good catch to James, Anthony, and Tadeck!
-- EDIT 2 --
Following the question update, I'd suggest adding another class to your links, i.e. clickable, then your CSS becomes:
.pc a.clickable:hover {
background-color: #FFF;
and you can just remove the clickable class on those links that you don't want to show the highlight. The better course of action may be to simply replace the links that are disabled with either raw text or as spans with an identifying class, i.e. disabled_link if you want to have the option to enable them later.
Though there was no HTML provided, based on the code, cB does not appear to be the element which has the class of pc but rather an ancestor of cB. You would need to remove the class from that.
If the direct parent is the only ancestor with the class of pc, you can do the following:
cB.parent().removeClass("pc")
If only one ancestor other than the direct parent has the class of pc and the parent does not, you can do the following:
cB.closest(".pc").removeClass("pc")
If multiple ancestors have the pc class, you can use the following:
cB.parents(".pc").removeClass("pc")
And finally, if multiple a tags exist within .pc then you cannot use the approach of removing the class, as this will affect all a tags within that .pc.
cB.removeClass('pc') should indeed remove aclass. Make sure your css behaves correctly in all scenarios. Also try targeting the parent
I would add a disabled class to the CSS that comes after the :hover rule and overrides it with the disabled styles, which may or may not be the default. Then, you can just do:
cB.addClass('disabled');
The reason your existing solution doesn't work is because you're removing the class from the element when its parent has the class.
Since your CSS issue was already solved, I want to point out another improvement:
I see that you are using cB.attr('data-f') to store some data, but attr should only be used for valid HTML attributes. You should consider using the jQuery data method which was created just for the purpose of storing non-attribute data into an element.
http://api.jquery.com/jQuery.data/
<p id="example">This is an example.</p>
<script>
document.getElementById('example').style.borderWidth = '4px';
</script>
Note that borderWidth is different than border-width. This can be used for the other styles. As a rule of thumb, take away the dash and make the first letter of the second word capital. If it doesn't work, Google it.
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).