Automatically persist Angular ng-models between sessions using local storage.

persist-directive

/**
 * Usage examples:
 * 
 * <input type="text" ng-model="someText" persist></input>
 * 
 * You can also specify a type to cast the value to:
 * <input type="num" ng-model="aNumber" persist="int"></input>
 * 
 * Valid types include:
 * 
 * - bool | boolean
 * - int | integer
 * - object | json
 * 
 * Note: If you change the name of the directive, you must also change the line `type = attrs.persist || 'string',` to match the new name.
 */

.directive('persist', function () {
    return {
        restrict: 'A',
        link: function (scope, elem, attrs) {
            var model = attrs.ngModel,
                key = '__scopePersist_' + model,
                value = localStorage[key],
                type = attrs.persist || 'string',
                castValue;

            if (value) {
                switch (type) {
                    case 'bool':
                    case 'boolean':
                        castValue = 'true' === value;
                        break;
                    case 'int':
                    case 'integer':
                        castValue = parseInt(value, 10);
                        break;
                    case 'object':
                    case 'json':
                        castValue = JSON.parse(value);
                        break;
                    default:
                        castValue = value;
                }

                scope[model] = castValue;
            }

            scope.$watch(model, function (value) {
                localStorage[key] = value;
            });
        }
    };
});