Show Search Button when Search Field is Non-Empty

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I think the :placeholder-shown selector is tremendously cool. It allows you to select the placeholder of an input (<input placeholder="...">) when that placeholder is present. Meaning, the input does not yet have any value. You might think input[value] could do that, or help match on the actual value, but it can't.

This makes :placeholder-shown one of the few CSS properties that we have that can react to user-initiated state joining the likes of :hover-and-friends, :checked (checkbox hack!), and the also-awesome :focus-within.

One way we can use it is to check whether the user entered any text into a search field. If yes, then reveal the search button visually (never hide it for assistive tech). If no, then leave it hidden. It's just a fun little "space-saving" technique not terrible unlike float labels.

So, perhaps we start with a semantic search form:

<form action="#" method="GET" class="search-form">
  <!-- Placeholders aren't labels! So let's have a real label -->
  <label for="search" class="screen-reader-text">Search</label>
  <input id="search" type="search" class="search-input" placeholder="Enter search terms...">
  <button class="search-button">Search</button>
</form>

We hide the search label visually with one of those special screen-reader-only classes because it will always be hidden visually. But we'll hide the button by pushing it outside the form with hidden overflow.

.search-form {
  /* we'll re-use this number, so DRYing up */
  --searchButtonWidth: 75px;

  overflow: hidden;
  position: relative;
}

.search-input {
  /* take full width of form */
  width: 100%;
}

.search-button {
  position: absolute; 
  /* push outside the form, hiding it */
  left: 100%;
  width: var(--searchButtonWidth);
}

Then the trick is to pull the search button back in when the placeholder goes away (user has entered a value):

/* ... */

.search-input:not(:placeholder-shown) ~ .search-button {
  /* pull back the negative value of the width */
  transform: translateX(calc(-1 * var(--searchButtonWidth)));
}
.search-button {
  position: absolute; 
  left: 100%;
  width: var(--searchButtonWidth);
  /* animate it */
  transition: 0.2s;
}

Which ends up like this:

See the Pen
:placeholder-shown revealing button by Chris Coyier (@chriscoyier)
on CodePen.

I saw this idea in a Pen by Liam Johnston. Cool idea, Liam!

I know that using the placeholder attribute at all is questionable, so your mileage may vary. I'll admit that I'm mostly intrigued by the state-handling aspects of it directly in CSS and how it can be used — like the infamous checkbox hack.

Support is good. One of those where when Edge is firmly Chromium, it's in the clear.

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