Toggle checked, selected, disabled, checked, readonly, multiple, etc…

toggle-attr.js

/**
 * toggleAttr() jQuery Plugin
 * 
 * Toggle checked, selected, disabled, checked, readonly, multiple, etc…
 */
jQuery.fn.toggleAttr = function (attr) {
    return this.each(function () {
        var $this = $(this);
        if ($this.attr(attr)) {
            $this.removeAttr(attr);
        } else {
            $this.attr(attr, attr);
        }
    });
};