Why and How the Bootstrap sr-only Class is Used
Usage of the sr-only class
According to the Bootstrap documentation, the sr-only class is used to hide information that is intended only for screen readers from the layout of a rendered page.
If you do not include a label for every input, screen readers may have trouble with the forms. For such inline forms, you can hide labels with the sr-only class.
You must always consider screen readers for accessibility purposes. Usage of this class will hide the element, and thus, you won’t see a visual difference.
Example of using the sr-only class in Bootstrap 3.4.1:
<!DOCTYPE html>
<html>
<head>
<meta name="viewport" content="width=device-width, initial-scale=1, maximum-scale=1, user-scalable=no">
<link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/3.4.1/css/bootstrap.min.css" integrity="sha384-HSMxcRTRxnN+Bdg0JdbxYKrThecOKuH5zCYotlSAcp1+c8xmyTe9GYg1l9a69psu" crossorigin="anonymous">
<style>
.sr-only {
position: absolute;
width: 1px;
height: 1px;
padding: 0;
margin: -1px;
overflow: hidden;
clip: rect(0, 0, 0, 0);
border: 0;
}
</style>
</head>
<body>
<div class="btn-group">
<button type="button" class="btn btn-info btn-md">Books</button>
<button type="button" class="btn btn-info dropdown-toggle btn-md" data-toggle="dropdown">
<span class="caret"></span>
<span class="sr-only">Toggle Dropdown</span>
</button>
<ul class="dropdown-menu" role="menu">
<li>
<a href="#">HTML</a>
</li>
<li>
<a href="#">CSS</a>
</li>
<li class="divider"></li>
<li>
<a href="#">Show all</a>
</li>
</ul>
</div>
</body>
</html>Example of using the sr-only class in Bootstrap 4.5.0:
<!DOCTYPE html>
<html>
<head>
<title>Title of the document</title>
<link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.5.0/css/bootstrap.min.css"
integrity="sha384-9aIt2nRpC12Uk9gS9baDl411NQApFmC26EwAOH8WgZl5MYYxFfc+NcPb1dKGj7Sk"
crossorigin="anonymous">
<style>
body {
background: #f5f5f5;
}
</style>
</head>
<body>
<h1>example</h1>
<form>
<div class="form-row align-items-center">
<div class="col-sm-3 my-1">
<label class="sr-only" for="inlineFormInputName">Name</label>
<input type="text" class="form-control" id="inlineFormInputName" placeholder="Jane Doe">
</div>
<div class="col-sm-3 my-1">
<label class="sr-only" for="inlineFormInputGroupUsername">Username</label>
<div class="input-group">
<div class="input-group-prepend">
<div class="input-group-text">@</div>
</div>
<input type="text" class="form-control" id="inlineFormInputGroupUsername" placeholder="Username">
</div>
</div>
<div class="col-auto my-1">
<div class="form-check">
<input class="form-check-input" type="checkbox" id="autoSizingCheck2">
<label class="form-check-label" for="autoSizingCheck2">
Remember me
</label>
</div>
</div>
<div class="col-auto my-1">
<button type="submit" class="btn btn-primary">Submit</button>
</div>
</div>
</form>
<script src="https://code.jquery.com/jquery-3.5.1.slim.min.js" integrity="sha384-DfXdz2htPH0lsSSs5nCTpuj/zy4C+OGpamoFVy38MVBnE+IbbVYUew+OrCXaRkfj" crossorigin="anonymous"></script>
<script src="https://cdn.jsdelivr.net/npm/[email protected]/dist/umd/popper.min.js" integrity="sha384-Q6E9RHvbIyZFJoft+2mJbHaEWldlvI9IOYy5n3zV9zzTtmI3UksdQRVvoxMfooAo" crossorigin="anonymous"></script>
<script src="https://stackpath.bootstrapcdn.com/bootstrap/4.5.0/js/bootstrap.min.js" integrity="sha384-OgVRvuATP1z7JjHLkuOU7Xw704+h835Lr+6QL9UvYjZE3Ipu6Tp75j7Bh/kR0JKI" crossorigin="anonymous"></script>
</body>
</html>