resources/src/mediawiki.storage.js

   1 ( function () {
   2         'use strict';
   3
   4         // Catch exceptions to avoid fatal in Chrome's "Block data storage" mode
   5         // which throws when accessing the localStorage property itself, as opposed
   6         // to the standard behaviour of throwing on getItem/setItem. (T148998)
   7         var
   8                 localStorage = ( function () {
   9                         try {
  10                                 return window.localStorage;
  11                         } catch ( e ) {}
  12                 }() ),
  13                 sessionStorage = ( function () {
  14                         try {
  15                                 return window.sessionStorage;
  16                         } catch ( e ) {}
  17                 }() );
  18
  19         /**
  20          * A wrapper for an HTML5 Storage interface (`localStorage` or `sessionStorage`)
  21          * that is safe to call on all browsers.
  22          *
  23          * @class mw.SafeStorage
  24          * @private
  25          * @param {Object|undefined} store The Storage instance to wrap around
  26          */
  27         function SafeStorage( store ) {
  28                 this.store = store;
  29         }
  30
  31         /**
  32          * Retrieve value from device storage.
  33          *
  34          * @param {string} key Key of item to retrieve
  35          * @return {string|null|boolean} String value, null if no value exists, or false
  36          *  if storage is not available.
  37          */
  38         SafeStorage.prototype.get = function ( key ) {
  39                 try {
  40                         return this.store.getItem( key );
  41                 } catch ( e ) {}
  42                 return false;
  43         };
  44
  45         /**
  46          * Set a value in device storage.
  47          *
  48          * @param {string} key Key name to store under
  49          * @param {string} value Value to be stored
  50          * @return {boolean} The value was set
  51          */
  52         SafeStorage.prototype.set = function ( key, value ) {
  53                 try {
  54                         this.store.setItem( key, value );
  55                         return true;
  56                 } catch ( e ) {}
  57                 return false;
  58         };
  59
  60         /**
  61          * Remove a value from device storage.
  62          *
  63          * @param {string} key Key of item to remove
  64          * @return {boolean} Whether the key was removed
  65          */
  66         SafeStorage.prototype.remove = function ( key ) {
  67                 try {
  68                         this.store.removeItem( key );
  69                         return true;
  70                 } catch ( e ) {}
  71                 return false;
  72         };
  73
  74         /**
  75          * Retrieve JSON object from device storage.
  76          *
  77          * @param {string} key Key of item to retrieve
  78          * @return {Object|null|boolean} Object, null if no value exists or value
  79          *  is not JSON-parseable, or false if storage is not available.
  80          */
  81         SafeStorage.prototype.getObject = function ( key ) {
  82                 var json = this.get( key );
  83
  84                 if ( json === false ) {
  85                         return false;
  86                 }
  87
  88                 try {
  89                         return JSON.parse( json );
  90                 } catch ( e ) {}
  91
  92                 return null;
  93         };
  94
  95         /**
  96          * Set an object value in device storage by JSON encoding
  97          *
  98          * @param {string} key Key name to store under
  99          * @param {Object} value Object value to be stored
 100          * @return {boolean} The value was set
 101          */
 102         SafeStorage.prototype.setObject = function ( key, value ) {
 103                 var json;
 104                 try {
 105                         json = JSON.stringify( value );
 106                         return this.set( key, json );
 107                 } catch ( e ) {}
 108                 return false;
 109         };
 110
 111         /**
 112          * A wrapper for the HTML5 `localStorage` interface
 113          * that is safe to call on all browsers.
 114          *
 115          * @class
 116          * @singleton
 117          * @extends mw.SafeStorage
 118          */
 119         mw.storage = new SafeStorage( localStorage );
 120
 121         /**
 122          * A wrapper for the HTML5 `sessionStorage` interface
 123          * that is safe to call on all browsers.
 124          *
 125          * @class
 126          * @singleton
 127          * @extends mw.SafeStorage
 128          */
 129         mw.storage.session = new SafeStorage( sessionStorage );
 130
 131 }() );