matches-selector.js

/**
 * matchesSelector v1.0.2
 * matchesSelector( element, '.selector' )
 * MIT license
 */

/*jshint browser: true, strict: true, undef: true, unused: true */
/*global define: false, module: false */

( function( ElemProto ) {

  'use strict';

  var matchesMethod = ( function() {
    // check un-prefixed
    if ( ElemProto.matchesSelector ) {
      return 'matchesSelector';
    }
    // check vendor prefixes
    var prefixes = [ 'webkit', 'moz', 'ms', 'o' ];

    for ( var i=0, len = prefixes.length; i < len; i++ ) {
      var prefix = prefixes[i];
      var method = prefix + 'MatchesSelector';
      if ( ElemProto[ method ] ) {
        return method;
      }
    }
  })();

  // ----- match ----- //

  function match( elem, selector ) {
    return elem[ matchesMethod ]( selector );
  }

  // ----- appendToFragment ----- //

  function checkParent( elem ) {
    // not needed if already has parent
    if ( elem.parentNode ) {
      return;
    }
    var fragment = document.createDocumentFragment();
    fragment.appendChild( elem );
  }

  // ----- query ----- //

  // fall back to using QSA
  // thx @jonathantneal https://gist.github.com/3062955
  function query( elem, selector ) {
    // append to fragment if no parent
    checkParent( elem );

    // match elem with all selected elems of parent
    var elems = elem.parentNode.querySelectorAll( selector );
    for ( var i=0, len = elems.length; i < len; i++ ) {
      // return true if match
      if ( elems[i] === elem ) {
        return true;
      }
    }
    // otherwise return false
    return false;
  }

  // ----- matchChild ----- //

  function matchChild( elem, selector ) {
    checkParent( elem );
    return match( elem, selector );
  }

  // ----- matchesSelector ----- //

  var matchesSelector;

  if ( matchesMethod ) {
    // IE9 supports matchesSelector, but doesn't work on orphaned elems
    // check for that
    var div = document.createElement('div');
    var supportsOrphans = match( div, 'div' );
    matchesSelector = supportsOrphans ? match : matchChild;
  } else {
    matchesSelector = query;
  }

  // transport
  if ( typeof define === 'function' && define.amd ) {
    // AMD
    define( function() {
      return matchesSelector;
    });
  } else if ( typeof exports === 'object' ) {
    module.exports = matchesSelector;
  }
  else {
    // browser global
    window.matchesSelector = matchesSelector;
  }

})( Element.prototype );