Showing posts with label sessionStorage. Show all posts
Showing posts with label sessionStorage. Show all posts
ngStorage - localStorage and sessionStorage done right for AngularJS

ngStorage - localStorage and sessionStorage done right for AngularJS

June 19, 2017
An AngularJS module that makes Web Storage working in the Angular Way. Contains two services: $localStorage and $sessionStorage.

Differences with Other Implementations

  • No Getter 'n' Setter Bullshit - Right from AngularJS homepage: "Unlike other frameworks, there is no need to [...] wrap the model in accessors methods. Just plain old JavaScript here." Now you can enjoy the same benefit while achieving data persistence with Web Storage.
  • sessionStorage - We got this often-overlooked buddy covered.
  • Cleanly-Authored Code - Written in the Angular Way, well-structured with testability in mind.
  • No Cookie Fallback - With Web Storage being readily available in all the browsers AngularJS officially supports, such fallback is largely redundant.

Install

Bower

 bower install ngstorage  
NOTE: We are ngstorage and NOT ngStorage. The casing is important!

NPM

 npm install ngstorage  
NOTE: We are ngstorage and NOT ngStorage. The casing is important!

nuget

 Install-Package gsklee.ngStorage  
Or search for Angular ngStorage in the nuget package manager. https://www.nuget.org/packages/gsklee.ngStorage

CDN

cdnjs

cdnjs now hosts ngStorage at https://cdnjs.com/libraries/ngStorage
To use it
 <script src="https://cdnjs.cloudflare.com/ajax/libs/ngStorage/0.3.6/ngStorage.min.js"></script>  

jsDelivr

jsDelivr hosts ngStorage at http://www.jsdelivr.com/#!ngstorage
To use is
 <script src="https://cdn.jsdelivr.net/ngstorage/0.3.6/ngStorage.min.js"></script>  

Usage

Require ngStorage and Inject the Services

 angular.module('app', [  
   'ngStorage'  
 ]).controller('Ctrl', function(  
   $scope,  
   $localStorage,  
   $sessionStorage  
 ){});  

Read and Write

Checkout a demo
Pass $localStorage (or $sessionStorage) by reference to a hook under $scope in plain ol' JavaScript:
 $scope.$storage = $localStorage;  
And use it like you-already-know:
 <body ng-controller="Ctrl">  
   <button ng-click="$storage.counter = $storage.counter + 1">{{$storage.counter}}</button>  
 </body>  
Optionally, specify default values using the $default() method:
 $scope.$storage = $localStorage.$default({  
   counter: 42  
 });  
With this setup, changes will be automatically sync'd between $scope.$storage, $localStorage, and localStorage - even across different browser tabs!

Read and Write Alternative (Not Recommended)

Checkout the demo If you're not fond of the presence of $scope.$storage, you can always use watchers:
 $scope.counter = $localStorage.counter || 42;  
 $scope.$watch('counter', function() {  
   $localStorage.counter = $scope.counter;  
 });  
 $scope.$watch(function() {  
   return angular.toJson($localStorage);  
 }, function() {  
   $scope.counter = $localStorage.counter;  
 });  
This, however, is not the way ngStorage is designed to be used with. As can be easily seen by comparing the demos, this approach is way more verbose, and may have potential performance implications as the values being watched quickly grow.

Delete

Checkout the demo Plain JavaScript again, what else could you better expect?
 // Both will do  
 delete $scope.$storage.counter;  
 delete $localStorage.counter;  
This will delete the corresponding entry inside the Web Storage.

Delete Everything

Checkout the demo If you wish to clear the Storage in one go, use the $reset() method:
 $localStorage.$reset();  
Optionally, pass in an object you'd like the Storage to reset to:
 $localStorage.$reset({  
   counter: 42  
 });  

Permitted Values

Checkout the demo You can store anything except those not supported by JSON:
  • Infinity, NaN - Will be replaced with null.
  • undefined, Function - Will be removed.

Usage from config phase

To read and set values during the Angular config phase use the .get/.set functions provided by the provider.
 var app = angular.module('app', ['ngStorage'])  
 .config(['$localStorageProvider',  
   function ($localStorageProvider) {  
     $localStorageProvider.get('MyKey');  
     $localStorageProvider.set('MyKey', { k: 'value' });  
   }]);  

Prefix

To change the prefix used by ngStorage use the provider function setKeyPrefix during the config phase.
 var app = angular.module('app', ['ngStorage'])  
 .config(['$localStorageProvider',  
   function ($localStorageProvider) {  
     $localStorageProvider.setKeyPrefix('NewPrefix');  
   }])  

Custom serialization

To change how ngStorage serializes and deserializes values (uses JSON by default) you can use your own functions.
 angular.module('app', ['ngStorage'])  
 .config(['$localStorageProvider',   
  function ($localStorageProvider) {  
   var mySerializer = function (value) {  
    // Do what you want with the value.  
    return value;  
   };  
   var myDeserializer = function (value) {  
    return value;  
   };  
   $localStorageProvider.setSerializer(mySerializer);  
   $localStorageProvider.setDeserializer(myDeserializer);  
  }];)  

Minification

Just run $ npm install to install dependencies. Then run $ grunt for minification.

Hints

Watch the watch
ngStorage internally uses an Angular watch to monitor changes to the $storage/$localStorage objects. That means that a digest cycle is required to persist your new values into the browser local storage. Normally this is not a problem, but, for example, if you launch a new window after saving a value...
 $scope.$storage.school = theSchool;  
 $log.debug("launching " + url);  
 var myWindow = $window.open("", "_self");  
 myWindow.document.write(response.data);  
the new values will not reliably be saved into the browser local storage. Allow a digest cycle to occur by using a zero-value $timeout as:
 $scope.$storage.school = theSchool;  
 $log.debug("launching and saving the new value" + url);  
 $timeout(function(){  
   var myWindow = $window.open("", "_self");  
   myWindow.document.write(response.data);  
 });  
or better using $scope.$evalAsync as:
 $scope.$storage.school = theSchool;  
 $log.debug("launching and saving the new value" + url);  
 $scope.$evalAsync(function(){  
   var myWindow = $window.open("", "_self");  
   myWindow.document.write(response.data);  
 });  
And your new values will be persisted correctly.

Note: Special thanks to G. Kay Lee

Contact - balancetraveller+github@gmail.com

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