Simplify ext.uls.preferences module

This is updated version of 61f1a9863a
which was reverted due to compatability issues which are no longer
present.

Change-Id: I05333ddc288171b6d867dce8a1d3efc1e1450e0a

resources/js/ext.uls.preferences.js

@@ -21,51 +21,11 @@
 ( function () {
 	'use strict';
 
-	var ULSPreferences;
-
-	/**
-	 * Wrapper for localStorage, falls back to cookie
-	 * when localStorage not supported by browser.
-	 *
-	 * @return {Object}
-	 */
-	function preferenceStore() {
-
-		// If value is detected, set new or modify store
-		return {
-			/*
-			 * Set the value to the given key
-			 * @param {string} key
-			 * @param {Object} value value to be set
-			 */
-			set: function ( key, value ) {
-				// Convert object values to JSON
-				if ( typeof value === 'object' ) {
-					value = JSON.stringify( value );
-				}
-
-				try {
-					localStorage.setItem( key, value );
-				} catch ( e ) {}
-			},
-			/*
-			 * Returns the value of the given key
-			 * @param {string} key
-			 * @return {Object} value of the key
-			 */
-			get: function ( key ) {
-				var data;
-
-				try {
-					data = JSON.parse( localStorage.getItem( key ) );
-				} catch ( e ) {}
-
-				return data;
-			}
-		};
-	}
+	var ULSPreferences, instance;
 
 	ULSPreferences = function () {
+		// This violates coding conventions for localstorage:
+		// https://www.mediawiki.org/wiki/Manual:Coding_conventions/JavaScript#Keys
 		this.preferenceName = 'uls-preferences';
 		this.username = mw.user.getName();
 		this.isAnon = mw.user.isAnon();
@@ -74,28 +34,19 @@
 	};
 
 	ULSPreferences.prototype = {
-		/**
-		 * Initialize
-		 */
 		init: function () {
-			var options;
-
 			if ( this.isAnon ) {
-				this.preferences = preferenceStore().get( this.preferenceName );
+				this.preferences = mw.storage.getObject( this.preferenceName );
 			} else {
-				options = mw.user.options.get( this.preferenceName );
-				if ( !options ) {
-					options = '{}';
-				}
-				// Try to parse JSON
 				try {
-					this.preferences = JSON.parse( options );
+					this.preferences = JSON.parse( mw.user.options.get( this.preferenceName ) );
 				} catch ( e ) {
-					this.preferences = {};
 				}
 			}
 
-			this.preferences = this.preferences || {};
+			if ( !$.isPlainObject( this.preferences ) ) {
+				this.preferences = {};
+			}
 		},
 
 		/**
@@ -124,34 +75,29 @@
 		 * @param {Function} callback
 		 */
 		save: function ( callback ) {
-			var ulsPreferences = this;
+			var self = this;
 
 			callback = callback || function () {};
 			if ( this.isAnon ) {
 				// Anonymous user. Save preferences in local storage
-				preferenceStore().set( this.preferenceName, this.preferences );
+				mw.storage.setObject( this.preferenceName, this.preferences );
 				callback.call( this, true );
 			} else {
 				// Logged in user. Use MW APIs to change preferences
 				new mw.Api().saveOption(
-					ulsPreferences.preferenceName,
-					JSON.stringify( ulsPreferences.preferences )
+					this.preferenceName,
+					JSON.stringify( this.preferences )
 				).done( function () {
-					callback.call( this, true );
+					callback.call( self, true );
 				} ).fail( function () {
-					callback.call( this, false );
+					callback.call( self, false );
 				} );
 			}
 		}
 	};
 
 	module.exports = function () {
-		var data = $( document.body ).data( 'preferences' );
-
-		if ( !data ) {
-			$( document.body ).data( 'preferences', ( data = new ULSPreferences() ) );
-		}
-		return data;
+		instance = instance || new ULSPreferences();
+		return instance;
 	};
-
 }() );