plusastab.joelpurra.js

/*!
* @license PlusAsTab
* Copyright (c) 2011, 2012, 2013, 2014, 2015, 2016, 2017 The Swedish Post and Telecom Authority (PTS)
* Developed for PTS by Joel Purra <https://joelpurra.com/>
* Released under the BSD license.
*
* A jQuery plugin to use the numpad plus key as a tab key equivalent.
*/

/* global
jQuery,
*/

// Set up namespace, if needed
var JoelPurra = JoelPurra || {};

(function($, namespace)
{
    // Private functions
    function performEmulatedTabbing(isTab, isReverse, $target) {
        isTab = (isTab === true);
        isReverse = (isReverse === true);

        if (isTab
                && $target !== undefined
                && $target.length !== 0) {
            $target.emulateTab(isReverse ? -1 : +1);

            return true;
        }

        return false;
    }

    function isChosenTabkey(key) {
        if (key === options.key
                || ($.isArray(options.key)
                    && $.inArray(key, options.key) !== -1)) {
            return true;
        }

        return false;
    }

    function isEmulatedTabkey(event) {
            // Checked later for reverse tab
            //&& !event.shiftKey

        if (!event.altKey
                && !event.ctrlKey
                && !event.metaKey
                && isChosenTabkey(event.which)) {
            return true;
        }

        return false;
    }

    function checkEmulatedTabKeyDown(event) {
        if (!isEmulatedTabkey(event)) {
            return;
        }

        var $target = $(event.target),
            wasDone = null;

        if ($target.is(disablePlusAsTab)
                || $target.parents(disablePlusAsTab).length > 0
                || (!$target.is(enablePlusAsTab)
                    && $target.parents(enablePlusAsTab).length === 0)) {
            return;
        }

        wasDone = performEmulatedTabbing(true, event.shiftKey, $target);

        if (wasDone) {
            event.preventDefault();
            event.stopPropagation();
            event.stopImmediatePropagation();

            return false;
        }

        return;
    }

    function initializeAtLoad() {
        $(document).on("keydown" + eventNamespace, checkEmulatedTabKeyDown);
    }

    namespace.PlusAsTab = {};

    var eventNamespace = ".PlusAsTab",

        // Keys from
        // https://api.jquery.com/event.which/
        // https://developer.mozilla.org/en/DOM/KeyboardEvent#Virtual_key_codes
        KEY_NUM_PLUS = 107,

        // Add options defaults here
        internalDefaults = {
            key: KEY_NUM_PLUS,
        },

        options = $.extend(true, {}, internalDefaults),

        enablePlusAsTab = ".plus-as-tab, [data-plus-as-tab=true]",
        disablePlusAsTab = ".disable-plus-as-tab, [data-plus-as-tab=false]";

    // Public functions
    namespace.PlusAsTab.setOptions = function(userOptions) {
            // Merge the options onto the current options (usually the default values)
        $.extend(true, options, userOptions);
    };

    namespace.PlusAsTab.plusAsTab = function($elements, enable) {
        enable = (enable === undefined ? true : enable === true);

        return $elements.each(function() {
            var $this = $(this);

            $this
                .not(disablePlusAsTab)
                .not(enablePlusAsTab)
                .attr("data-plus-as-tab", enable ? "true" : "false");
        });
    };

    $.fn.extend({
        plusAsTab: function(enable) {
            return namespace.PlusAsTab.plusAsTab(this, enable);
        },
    });

    // PlusAsTab initializes listeners when jQuery is ready
    $(initializeAtLoad);
}(jQuery, JoelPurra));