• Element directives: This directive works upon confronting the matching element.
• CSS class directives: Starts working when the same CSS style matches.
• Comment directives: It activates when a matching comment comes up.
• Attribute directives: Attribute directives come into the picture upon confronting the matching/same directives.

AngularJS has below security features which are built-in and help in protecting your applications

• Automatic output encoding and input sanitization: AngularJS automatically encodes all output values before they are rendered in the DOM and sanitizes all input values before they are used in expressions. This helps to prevent cross-site scripting (XSS) attacks.
• CSRF protection: This feature prevents attackers from hijacking user sessions.
• JSON Hijacking protection: AngularJS protects against JSON Hijacking attacks by stripping a prefix from all JSON responses before they are processed. This prevents attackers from injecting malicious code into your application.
• Strict Contextual Escaping: Strict contextual escaping is provided for all expressions, which helps to prevent XSS attacks in a wider range of scenarios.
• Using Local Caches: AngularJS allows you to use local caches to store data that is not frequently changing. This can help to improve performance and security, as it reduces the number of requests that need to be made to the server.

Here are some of the most common directives in Angular:

• ng-app: This directive is used to mark the root element of an AngularJS application.
• ng-init: This directive is used to initialize application data.
• ng-model: This directive binds the value of an HTML element to a variable in AngularJS.
• ng-repeat: This directive repeats an HTML element for each item in a collection.
• ng-if: This directive conditionally renders an HTML element.
• ng-class: This directive dynamically adds or removes CSS classes from an HTML element.
• ng-style: This directive dynamically sets the style properties of an HTML element.
• ng-click: This directive attaches an event listener to an HTML element.
• ng-submit: This directive attaches an event listener to an HTML form element.

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<button ng-dblclick="enableButton()">Double Click Me</button>

The ng-dblclick directive tells AngularJS to execute the enableButton() function when the button is double-clicked. The enableButton() function can be used to enable or disable the button, or to perform any other desired action.

In this example, the enableButton() function simply sets the button's disabled property to false. This allows the button to be clicked again.

You can also use the ng-dblclick directive to prevent the button from being clicked twice in a short period of time. To do this, you can use the setTimeout() function to delay the execution of the enableButton() function.

For example, the following code will prevent the button from being clicked twice in a 200 millisecond period:

<button ng-dblclick="enableButton()">Double Click Me</button>

<script>

function enableButton() {

 setTimeout(function() {

   // Enable the button

   $("button").removeAttr("disabled");

 }, 200);

}

</script>

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While both the concepts deal with Asynchronous events in Angular, Promises handle one such event at a time while observables handle a sequence of events over some time.  

Promises - They emit a single value at a time. They execute immediately after creation and are not cancellable. They are Push errors to the child promises.  

Observables - They are only executed when subscribed to them using the subscribe() method. They emit multiple values over a period of time. They help perform operations like forEach, filter, and retry, among others. They deliver errors to the subscribers. When the unsubscribe() method is called, the listener stops receiving further values.

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To include SASS (Syntactically Awesome Style Sheets) into an Angular project, you need to install the required dependencies and configure the project accordingly. Follow these steps:

• Install the node-sass package by running the command npm install node-sass --save-dev.
• Update the angular.json file in your project's root directory.
• Locate the styles property under architect > build > options.
• Change the file extension from .css to .scss to indicate that you are using SASS.
• Rename your existing CSS files to SCSS files (e.g., styles.css to styles.scss).
• Restart the Angular development server for the changes to take effect.

Once SASS is included in your Angular project, you can write your styles using SASS syntax, which provides additional features like variables, mixins, and nested selectors.