https://iec.edu.in/blog/wp-content/themes/azure-news/assets/js/keyboard-accessibility.js?ver=1.0.2

1/**
2 * Follows the wordpress.org keyboard accessibility rules.
3 */
4jQuery(document).ready(function($) {
5
6    "use strict";
7    var KEYCODE_TAB = 9;
8
9    /**
10     * On click modal content toggler.
11     */
12    $( ".azure-news-modal-toggler" ).on( "click", function() {
13        var _this = $(this),
14        popupContent = _this.data("popup-content"),
15        focusToTrapIn = document.querySelector( ".azure-news-modal-popup-content.isActive" );
16        if( !focusToTrapIn ) return;
17        if( focusToTrapIn.length != 0 ) {
18            var focusable = focusElements( focusToTrapIn ),
19            initialFocusable = focusable[0],
20            finalFocusable = focusable[focusable.length - 1];
21            $( initialFocusable ).focus();
22            $(document).on('keydown', function(e) {
23                azure_news_accessibility_focus_trap( initialFocusable, finalFocusable, e );
24            });
25        }
26    });
27
28    /**
29     * On click modal close button
30     * stay focus on popup toggler
31     */
32    $( ".azure-news-modal-close" ).on( "click", function() {
33        var toFocus = $(this).data( "focus" );
34        $( toFocus ).focus();
35    });
36
37    /**
38     * Focus trap inside the popup content.
39     */
40    function azure_news_accessibility_focus_trap( initialFocusable, finalFocusable, e ) {
41        if ( e.key === 'Tab' || e.keyCode === KEYCODE_TAB ) {
42            if ( e.shiftKey ) /* shift + tab */ {
43                if (document.activeElement === initialFocusable) {
44                    finalFocusable.focus();
45                    e.preventDefault();
46                }
47            } else /* tab */ {
48                if ( document.activeElement === finalFocusable ) {
49                    initialFocusable.focus();
50                    e.preventDefault();
51                }
52            }
53        }
54    }
55
56    /**
57     * Get all focusable elements inside the element
58     */
59    function focusElements( focusToTrapIn ) {
60        return focusToTrapIn.querySelectorAll( 'button, [href], input, select, textarea, [tabindex]:not([tabindex="-1"])');
61    }
62
63});