How to Create an Angular Directive from a jQuery or JavaScript Plugin

What is a jQuery plugin?

A jQuery plugin is made up of methods that a jQuery object can inherit when a jQuery prototype object needs to be expanded. Several jQuery plugins are still accessible online for usage, however they can be built or adapted to meet specific needs. Consequently, the jQuery plugin may be viewed as a set of components that are referred to as methods or functions. All of the prototype’s methods as well as the inherited methods of the plugin are called simultaneously when a jQuery object is invoked.

What is AngularJS Directive?

There are many elements that are specified in AngularJS, however there may be occasions when it becomes necessary to expand the related HTML. Through a “directive” function that is invoked in place of the element for which it is specified, custom directives make this possible. Only after the linking (link() function) of the element and its directive function following the compilation (compile() function) procedure does this occur. The following components in AngularJS support custom directives:

  • Element: The directive begins to function when a matching element is discovered (restrict E)
  • Attribute: The directive begins to function when a matching attribute is detected (restrict A)
  • CSS: The directive starts operating when a matching CSS style is discovered (restrict C)
  • Comment: The directive starts working when it finds a comment that matches (restrict M)

A custom directive has a lot of benefits. The use of directives makes it easier to write repeatable, self-sufficient code. Whatever the needs, all the associated functions and properties are bundled together. Multiple directives, each with a particular scope and purpose, may exist in this fashion and be available for use as needed.

Typical startup of a jQuery plugin

A jQuery plugin is fairly simple to use when used alone. When considering its initialization, merely go for it in the document’s initialising event: document.ready.

<div  id="ng-slider"></div>  
<p>The slider's value is: <span  id="slider-value">0</span></p>    
$(document).ready(function() {  
    // Initialize the slider  
    $('#slider').slider({  
        change: function(event, ui) {  
            $('#slider-value').html(ui.value);  
        }  
     });  
});

When the Document Object Model (DOM) has loaded, the document.ready event takes place. After the document is prepared for execution, this happens. To begin the execution, all functions and sub-events can be included into this event.

A function that enables a slider object to modify its value when an event of its bar movement happens is called by the code mentioned above inside the ready event. That implies that the slider’s value in numbers adjusts when the slider’s bar is moved. As a result, this is where the jQuery plugin function initialises a slider object’s sliding value upon another action event.

How to create custom Directive?

Any jQuery plugin needs a directive in order to make the code more functional than what can be done with a custom directive,

app.directive('directiveName', function() {  
    return {  
        restrict: 'A',  
        link: function(scope, element, attrs) {  
            $(element).pluginInitFunction(params);  
        }  
      };  
});

A matching Attribute is sought by the directive (A). Restrict can take one of the four values—E, A, C, or M—but it can also combine them to form other values, such as CA, EC, or CM, for example.

Then, if there are several objects in the scope, the link function connects each element with the scope based on matching characteristics. Each each object or element is also initialised to a specific parameter.

The construction of a custom directive in AngularJS is the whole procedure. This specific directive code deals with the one-side route, or tying the directive to the plugin. However, we must establish two-way binding using the ‘$scope.$apply()’ function if we want to guarantee a bidirectional path, that is, if we want to make sure that any change in scope inside the plugin may be addressed by the directive. With each little adjustment to the plugin scope settings, the entire AngularJS cycle gets hooked.

Merge the jQuery plugin into Custom Directive 

It now needs that we combine a custom directive with a jQuery plugin that we previously created. You may achieve so by inserting the plugin initialization code within the directive’s link() method.

When the limitation is applied, the code for creating the custom directive mentioned above builds a specific template on the console and inserts the values for the jQuery plugin into the directive. Based on the results obtained, a specific scope is modified. This comes after the compilation procedure, which combines all the data from the custom directives and jQuery plugins. The full directive is then inserted into the HTML for syntax completion when linking is finished.

The AngularJS custom directive then links the two together with HTML and CSS to produce a functional environment for the jQuery plugin. Here is an example of a straightforward case study:

var app = angular.module('myapp', []);  
app.controller('myController', ['$scope', function($scope) {  
  $scope.sliderValue = 30;  
}]);  
app.directive('mySlider', function() {  
  return {  
    restrict: 'A',  
    scope: {  
      'model': '='  
    },  
    link: function(scope, elem, attrs) {  
      $(elem).slider({  
        value: +scope.model,  
        slide: function(event, ui) {  
          scope.$apply(function() {  
            scope.model = ui.value;  
            });  
           }  
         });  
       }  
      };  
 });

At the present, AngularJS is fairly popular. However, it has a flaw that may be fixed by utilising jQuery plugins. However, connecting is quite challenging since the two languages are so dissimilar. The jQuery plugins may be utilised pretty well with AngularJS directives, making the driving engine (directive code) repetitive and surely reusable in the future. In addition to being pre-made and accessible, directives can also be made specifically for you. The character of the directives is determined by their usage.

 

 

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