Css – Twitter Bootstrap Form File Element Upload Button

cssformsinput-type-filetwitter-bootstrap

Why isn't there a fancy file element upload button for twitter bootstrap? It would be sweet if the blue primary button was implemented for the upload button. Is it even possible to finesse the upload button using CSS? (seems like a native browser element that can't be manipulated)

Best Answer

Here's a solution for Bootstrap 3 and 4.

To make a functional file input control that looks like a button, you only need HTML:

HTML

<label class="btn btn-default">
    Browse <input type="file" hidden>
</label>

This works in all modern browsers, including IE9+. If you need support for old IE as well, please use the legacy approach shown below.

This techniques relies on the HTML5 hidden attribute. Bootstrap 4 uses the following CSS to shim this feature in unsupportive browsers. You may need to add if you're using Bootstrap 3.

[hidden] {
  display: none !important;
}

Legacy approach for old IE

If you need support for IE8 and below, use the following HTML/CSS:

HTML

<span class="btn btn-default btn-file">
    Browse <input type="file">
</span>

CSS

.btn-file {
    position: relative;
    overflow: hidden;
}
.btn-file input[type=file] {
    position: absolute;
    top: 0;
    right: 0;
    min-width: 100%;
    min-height: 100%;
    font-size: 100px;
    text-align: right;
    filter: alpha(opacity=0);
    opacity: 0;
    outline: none;
    background: white;
    cursor: inherit;
    display: block;
}

Note that old IE doesn't trigger the file input when you click on a <label>, so the The CSS "bloat" does a couple things to work around that:

Makes the file input span the full width/height of the surrounding <span>
Makes the file input invisible

Feedback & Additional Reading

I've posted more details about this method, as well as examples for how to show the user which/how many files are selected:

https://www.abeautifulsite.net/posts/whipping-file-inputs-into-shape-with-bootstrap-3/

Related Solutions

Javascript – How to force the browser to reload cached CSS and JavaScript files

This solution is written in PHP, but it should be easily adapted to other languages.

The original .htaccess regex can cause problems with files like json-1.3.js. The solution is to only rewrite if there are exactly 10 digits at the end. (Because 10 digits covers all timestamps from 9/9/2001 to 11/20/2286.)

First, we use the following rewrite rule in .htaccess:

RewriteEngine on
RewriteRule ^(.*)\.[\d]{10}\.(css|js)$ $1.$2 [L]

Now, we write the following PHP function:

/**
 *  Given a file, i.e. /css/base.css, replaces it with a string containing the
 *  file's mtime, i.e. /css/base.1221534296.css.
 *
 *  @param $file  The file to be loaded.  Must be an absolute path (i.e.
 *                starting with slash).
 */
function auto_version($file)
{
  if(strpos($file, '/') !== 0 || !file_exists($_SERVER['DOCUMENT_ROOT'] . $file))
    return $file;

  $mtime = filemtime($_SERVER['DOCUMENT_ROOT'] . $file);
  return preg_replace('{\\.([^./]+)$}', ".$mtime.\$1", $file);
}

Now, wherever you include your CSS, change it from this:

<link rel="stylesheet" href="/css/base.css" type="text/css" />

To this:

<link rel="stylesheet" href="<?php echo auto_version('/css/base.css'); ?>" type="text/css" />

This way, you never have to modify the link tag again, and the user will always see the latest CSS. The browser will be able to cache the CSS file, but when you make any changes to your CSS the browser will see this as a new URL, so it won't use the cached copy.

This can also work with images, favicons, and JavaScript. Basically anything that is not dynamically generated.

Html – Styling an input type=”file” button

You don't need JavaScript for this! Here is a cross-browser solution:

See this example! - It works in Chrome/FF/IE - (IE10/9/8/7)

The best approach would be to have a custom label element with a for attribute attached to a hidden file input element. (The label's for attribute must match the file element's id in order for this to work).

<label for="file-upload" class="custom-file-upload">
    Custom Upload
</label>
<input id="file-upload" type="file"/>

As an alternative, you could also just wrap the file input element with a label directly: (example)

<label class="custom-file-upload">
    <input type="file"/>
    Custom Upload
</label>

In terms of styling, just hide¹ the input element using the attribute selector.

input[type="file"] {
    display: none;
}

Then all you need to do is style the custom label element. (example).

.custom-file-upload {
    border: 1px solid #ccc;
    display: inline-block;
    padding: 6px 12px;
    cursor: pointer;
}

¹ - It's worth noting that if you hide the element using display: none, it won't work in IE8 and below. Also be aware of the fact that jQuery validate doesn't validate hidden fields by default. If either of those things are an issue for you, here are two different methods to hide the input (1, 2) that work in these circumstances.