:first selector

Selects the first matched element.

The :first pseudo-class is equivalent to :eq( 0 ). It could also be written as :lt( 1 ). While this matches only a single element, :first-child can match more than one: One for each parent.

Because :first is a jQuery extension and not part of the CSS specification, queries using :first cannot take advantage of the performance boost provided by the native DOM querySelectorAll() method. To achieve the best performance when using :first to select elements, first select the elements using a pure CSS selector, then use .filter(":first").
Selected elements are in the order of their appearance in the document.

jQuery( ":first" )

version added: 1.0

Examples:

Finds the first table row.

<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <title>first demo</title>
  <style>
  td {
    color: blue;
    font-weight: bold;
  }
  </style>
  <script src="https://code.jquery.com/jquery-1.10.2.js"></script>
</head>
<body>
 
<table>
  <tr><td>Row 1</td></tr>
  <tr><td>Row 2</td></tr>
  <tr><td>Row 3</td></tr>
</table>
 
<script>
$( "tr:first" ).css( "font-style", "italic" );
</script>
 
</body>
</html>

Links:

http://api.jquery.com/first-selector

doc_jQuery

2016-03-27 13:48:22

Comments