>>Hi everybody,
>>
>>I am still not clear how directives work and how to make them optional.
>
>The link function passes a third parameter which lets you get at the attributes:
>
>

>// Instead of this:
>            link: function (scope, element) {
>// Do this:
>            link: function (scope, element, attrib) {
>

>
>Now you have access to the attributes, so to grab the value:
>
>

>var attribValue = attrib.smFocus
>

>
>(take a look at attrib in the debugger and you'll see the values it holds).

Now instead of evaluating the "isNew" variable the attribute is now "isNew". What should I do? Here is my new code:

(function () {
    'use strict';

    var app = angular.module('sysMgrApp');

    app.directive('smFocus', [ '$timeout', function ($timeout) {
        return {
            restrict: 'A',

            link: function (scope, element, attribute) {
                var attribValue = attribute.smFocus;

                console.log('Element Id= ' + element[0].attributes["id"].value + ' attribValue=' + attribValue);
                if (attribValue=='' || attribValue == true) {
                    scope.$on('sm:focus', function () {
                        $timeout(function () {
                            element[0].focus();
                        }, 10);
                    });
                }
            }
        };
    }]);
})();

and this is the element's markup in the form:

 <div class="form-group">
            <div class="control-label col-lg-3">
                <label title="Nickname">Nickname:</label>
            </div>
            <div class="controls">
                <div class="col-lg-9">
                    <input type="text"
                           name="nickname"
                           id="nickname"
                           ng-model="currentDynamicRule.nickname"
                           class="form-control"
                           ng-disabled="!isNew"
                           placeholder="Nickname"
                           required
                           ng-maxlength="10"                           
                           data-sm:focus="isNew" />
                    <div class="field-validation-error">
                        <span ng-show="form.editDynamicRule.nickName.$error.required && form.editDynamicRule.nickName.$dirty">Nickname is required.</span>
                        <span ng-show="form.editDynamicRule.nickName.$error.maxlength && form.editDynamicRule.nickName.$dirty">Nickname cannot exceed 10 characters.</span>
                    </div>
                </div>
            </div>
        </div>

I see the attribute now is "isNew" instead of false (the value of isNew variable).