Showing posts with label ngReact. Show all posts
Showing posts with label ngReact. Show all posts
Use React Components in Angular - ngReact

Use React Components in Angular - ngReact

May 18, 2017

The React.js library can be used as a view component in web applications. ngReact is an Angular module that allows React Components to be used in AngularJS applications.
Motivation for this could be any of the following:
  • You need greater performance than Angular can offer (two way data binding, Object.observe, too many scope watchers on the page) and React is typically more performant due to the Virtual DOM and other optimizations it can make
  • React offers an easier way to think about the state of your UI; instead of data flowing both ways between controller and view as in two way data binding, React typically eschews this for a more unidirectional/reactive paradigm
  • Someone in the React community released a component that you would like to try out
  • You're already deep into an Angular application and can't move away, but would like to experiment with React


Installation


Install via Bower:
 bower install ngReact  
or via npm:
 npm install ngreact  


Usage


Then, just make sure Angular, React, and ngReact are on the page,
 <script src="bower_components/angular/angular.js"></script>  
 <script src="bower_components/react/react.js"></script>  
 <script src="bower_components/react/react-dom.js"></script>  
 <script src="bower_components/ngReact/ngReact.min.js"></script>  
and include the 'react' Angular module as a dependency for your new app
 <script>  
   angular.module('app', ['react']);  
 </script>  
and you're good to go.

Features


Specifically, ngReact is composed of:
  • react-component, an Angular directive that delegates off to a React Component
  • reactDirective, a service for converting React components into the react-component Angular directive
ngReact can be used in existing angular applications, to replace entire or partial views with react components.

The react-component directive


The react-component directive is a generic wrapper for embedding your React components.
With an Angular app and controller declaration like this:
 angular.module('app', ['react'])  
  .controller('helloController', function($scope) {  
   $scope.person = { fname: 'Clark', lname: 'Kent' };  
  });  
And a React Component like this
 var HelloComponent = React.createClass({  
  propTypes: {  
   fname : React.PropTypes.string.isRequired,  
   lname : React.PropTypes.string.isRequired  
  },  
  render: function() {  
   return <span>Hello {this.props.fname} {this.props.lname}</span>;  
  }  
 })  
 app.value('HelloComponent', HelloComponent);  
The component can be used in an Angular view using the react-component directive like so:
 <body ng-app="app">  
  <div ng-controller="helloController">  
   <react-component name="HelloComponent" props="person" watch-depth="reference"/>  
  </div>  
 </body>  
Here:
  • name attribute checks for an Angular injectable of that name and falls back to a globally exposed variable of the same name
  • props attribute indicates what scope properties should be exposed to the React component
  • watch-depth attribute indicates what watch strategy to use to detect changes on scope properties. The possible values for react-component are reference, collection and value (default)


The reactDirective service


The reactDirective factory, in contrast to the reactComponent directive, is meant to create specific directives corresponding to React components. In the background, this actually creates and sets up directives specifically bound to the specified React component.
If, for example, you wanted to use the same React component in multiple places, you'd have to specify repeatedly, but if you used reactDirective factory, you could create a directive and simply use that everywhere.
The service takes the React component as the argument.
 app.directive('helloComponent', function(reactDirective) {  
  return reactDirective(HelloComponent);  
 });  
Alternatively you can provide the name of the component
 app.directive('helloComponent', function(reactDirective) {  
  return reactDirective('HelloComponent');  
 });  
This creates a directive that can be used like this:
 <body ng-app="app">  
  <div ng-controller="helloController">  
   <hello-component fname="person.fname" lname="person.lname" watch-depth="reference"></hello-component>  
  </div>  
 </body>  
The reactDirective service will read the React component propTypes and watch attributes with these names. If your react component doesn't have propTypes defined you can pass in an array of attribute names to watch. By default, attributes will be watched by value however you can also choose to watch by reference or collection by supplying the watch-depth attribute. Possible values are reference, collection and value (default).
 app.directive('hello', function(reactDirective) {  
  return reactDirective(HelloComponent, ['fname', 'lname']);  
 });  
You may also customize the watch depth per prop/attribute by wrapping the name and an options object in an array inside the props array:
 app.directive('hello', function(reactDirective) {  
  return reactDirective(HelloComponent, [  
   'person', // takes on the watch-depth of the entire directive  
   ['place', {watchDepth: 'reference'}],  
   ['things', {watchDepth: 'collection'}],  
   ['ideas', {watchDepth: 'value'}]  
  ]);  
 });  
If you want to change the configuration of the directive created the reactDirective service, e.g. change restrict: 'E' to restrict: 'C', you can do so by passing in an object literal with the desired configuration.
 app.directive('hello', function(reactDirective) {  
  return reactDirective(HelloComponent, undefined, {restrict: 'C'});  
 });  


Minification


A lot of automatic annotation libraries including ng-annotate skip implicit annotations of directives. Because of that you might get the following error when using directive in minified code:
 Unknown provider: eProvider <- e <- helloDirective  
To fix it add explicit annotation of dependency
 var helloDirective = function(reactDirective) {  
  return reactDirective('HelloComponent');  
 };  
 helloDirective.$inject = ['reactDirective'];  
 app.directive('hello', helloDirective);  


Reusing Angular Injectables


In an existing Angular application, you'll often have existing services or filters that you wish to access from your React component. These can be retrieved using Angular's dependency injection. The React component will still be render-able as aforementioned, using the react-component directive.
It's also possible to pass Angular injectables and other variables as fourth parameter straight to the reactDirective, which will then attach them to the props
 app.directive('helloComponent', function(reactDirective, $ngRedux) {  
  return reactDirective(HelloComponent, undefined, {}, {store: $ngRedux});  
 });  
Be aware that you can not inject Angular directives into JSX.
 app.filter('hero', function() {  
  return function(person) {  
   if (person.fname === 'Clark' && person.lname === 'Kent') {  
    return 'Superman';  
   }  
   return person.fname + ' ' + person.lname;  
  };  
 });  
 /** @jsx React.DOM */  
 app.factory('HelloComponent', function($filter) {  
  return React.createClass({  
   propTypes: {  
    person: React.PropTypes.object.isRequired,  
   },  
   render: function() {  
    return <span>Hello $filter('hero')(this.props.person)</span>;  
   }  
  });  
 });  
 <body ng-app="app">  
  <div ng-controller="helloController">  
   <react-component name="HelloComponent" props="person" />  
  </div>  
 </body>  


Jsx Transformation in the browser


During testing you may want to run the JSXTransformer in the browser. For this to work with angular you need to make sure that the jsx code has been transformed before the angular application is bootstrapped. To do so you can manually bootstrap the angular application. For a working example see the jsx-transformer example. NOTE: The workaround for this is hacky as the angular bootstap is postponed in with a setTimeout, so consider transforming jsx in a build step.

Usage with webpack and AngularJS < 1.3.14


CommonJS support was added to AngularJS in version 1.3.14. If you use webpack and need to support AngularJS < 1.3.14, you should use webpack's exports-loader so that require('angular') returns the correct value. Your webpack configuration should include the following loader config:
 ...  
 module: {  
  loaders: [  
   {  
    test: path.resolve(__dirname, 'node_modules/angular/angular.js'),  
    loader: 'exports?window.angular'  
   }  
  ]  
 },  
 ...  


Developing


Before starting development run
 npm install  
 bower install  
Build minified version and run tests with
 grunt  
Continually run test during development with
 grunt karma:background watch  


Note: Special thanks to ngReact

Disclaimer: The blog is created to share angular directives information to geek, curious Angular Developer.