Can I use a :before or :after pseudo-element on an input field?

:before and :after render inside a container

and can not contain other elements.

Pseudo-elements can only be defined (or better said are only supported) on container elements. Because the way they are rendered is within the container itself as a child element. input can not contain other elements hence they're not supported. A button on the other hand that's also a form element supports them, because it's a container of other sub-elements.

If you ask me, if some browser does display these two pseudo-elements on non-container elements, it's a bug and a non-standard conformance. Specification directly talks about element content...

W3C specification

If we carefully read the specification it actually says that they are inserted inside a containing element:

Authors specify the style and location of generated content with the :before and :after pseudo-elements. As their names indicate, the :before and :after pseudo-elements specify the location of content before and after an element's document tree content. The 'content' property, in conjunction with these pseudo-elements, specifies what is inserted.

See? an element's document tree content. As I understand it this means within a container.

:after and :before are not supported in Internet Explorer 7 and under, on any elements.

It's also not meant to be used on replaced elements such as form elements (inputs) and image elements.

In other words it's impossible with pure CSS.

However if using jquery you can use

$(".mystyle").after("add your smiley here");

API docs on .after

To append your content with javascript. This will work across all browsers.

Oddly, it works with some types of input. At least in Chrome,

<input type="checkbox" />

works fine, same as

<input type="radio" />

It's just type=text and some others that don't work.

Here's another approach (assuming you have control of the HTML): add an empty <span></span> right after the input, and target that in CSS using input.mystyle + span:after

.field_with_errors { display: inline; color: red; } .field_with_errors input+span:after { content: "*" }

I'm using this approach in AngularJS because it will add .ng-invalid classes automatically to <input> form elements, and to the form, but not to the <label>.

:before and :after are applied inside a container, which means you can use it for elements with an end tag.

It doesn't apply for self-closing elements.

On a side note, elements which are self-closing (such as img/hr/input) are also known as 'Replaced Elements', as they are replaced with their respective content. "External Objects" for the lack of a better term. A better read here

I used the background-image to create the red dot for required fields.

input[type="text"][required] {
  background-image: radial-gradient(red 15%, transparent 16%);
  background-size: 1em 1em;
  background-position: top right;
  background-repeat: no-repeat
}

View on Codepen

Pseudo elements like :after, :before are only for container elements. Elements starting and closing in a single place like <input/>, <img> etc are not container elements and hence pseudo elements are not supported. Once you apply a pseudo element to container element like <div> and if you inspect the code(see the image) you can understand what I mean. Actually the pseudo element is created inside the container element. This is not possible in case of <input> or <img>

https://i.stack.imgur.com/1yUox.png

The biggest misunderstanding here is the meaning of the words before and after. They do not refer to the element itself, but to the content in the element. So element:before is before the content, and element:after is after the content, but both are still inside the original element.

The input element has no content in the CSS view, and so has no :before or :after pseudo content. This is true of many other void or replaced elements.

There is no pseudo element referring to outside the element.

In a different universe, these pseudo elements might have been called something else to make this distinction clearer. And someone might even have proposed a pseudo element which is genuinely outside the element. So far, this is not the case in this universe.

You can't put a pseudo element in an input element, but can put in shadow element, like a placeholder!

input[type="text"] {   
  &::-webkit-input-placeholder {
    &:before {
      // your code
    }
  }
}

To make it work in other browsers, use :-moz-placeholder, ::-moz-placeholder and :-ms-input-placeholder in different selectors. Can't group the selectors, because if a browser doesn't recognize the selector invalidates the entire statement.

UPDATE: The above code works only with CSS pre-processor (SASS, LESS...), without pre-processors use:

input[type="text"]::-webkit-input-placeholder:before { // your code }

A working solution in pure CSS:

The trick is to suppose there's a dom element after the text-field.

/* * The trick is here: * this selector says "take the first dom element after * the input text (+) and set its before content to the * value (:before). */ input#myTextField + *:before { content: "👍"; }

(*) Limited solution, though:

you have to hope that there's a following dom element,

you have to hope no other input field follows your input field.

But in most cases, we know our code so this solution seems efficient and 100% CSS and 0% jQuery.

I found this post as I was having the same issue, this was the solution that worked for me. As opposed to replacing the input's value just remove it and absolutely position a span behind it that is the same size, the span can have a :before pseudo class applied to it with the icon font of your choice.

<style type="text/css">

form {position: relative; }
.mystyle:before {content:url(smiley.gif); width: 30px; height: 30px; position: absolute; }
.mystyle {color:red; width: 30px; height: 30px; z-index: 1; position: absolute; }
</style>

<form>
<input class="mystyle" type="text" value=""><span class="mystyle"></span>
</form>

According to a note in the CSS 2.1 spec, the specification “does not fully define the interaction of :before and :after with replaced elements (such as IMG in HTML). This will be defined in more detail in a future specification.” Although input is not really a replaced element any more, the basic situation has not changed: the effect of :before and :after on it in unspecified and generally has no effect.

The solution is to find a different approach to the problem you are trying to address this way. Putting generated content into a text input control would be very misleading: to the user, it would appear to be part of the initial value in the control, but it cannot be modified – so it would appear to be something forced at the start of the control, but yet it would not be submitted as part of form data.

As others explained, inputs are kinda-replaced void elements, so most browsers won't allow you to generate ::before nor ::after pseudo-elements in them.

However, the CSS Working Group is considering explicitly allowing ::before and ::after in case the input has appearance: none.

From https://lists.w3.org/Archives/Public/www-style/2016Mar/0190.html,

Safari and Chrome both allow pseudo-elements on their form inputs. Other browsers don't. We looked into removing this, but the use-counter is recording ~.07% of pages using it, which is 20x our max removal threshold. Actually specifying pseudo-elements on inputs would require specifying the internal structure of inputs at least somewhat, which we haven't managed to do yet (and I'm not confident we *can* do). But Boris suggested, in one of the bugthreads, allowing it on appearance:none inputs - basically just turning them into