ionSlider.directive

ng-ionSlider.js

angular.module('directive.ionSlider', []).directive('ionSlider', ['$document', function($document) {
    "use strict";
    return {
        restrict: 'EA',
        require: 'ngModel',
        template: '<input type="text" />',
        link: function(scope, element, attrs, ngModel) {
            var input = element.find('input'),
                isDouble = attrs.type === 'double';
            input.ionRangeSlider({
                grid: true,
                hide_min_max: true,
                values: scope.$eval(attrs.values),
                min_prefix: attrs.minPrefix,
                max_prefix: attrs.maxPrefix,
                min_postfix: attrs.minPostfix,
                max_postfix: attrs.maxPostfix,
                min: +attrs.min,
                max: +attrs.max,
                type: attrs.type
            });
            var slider = input.data("ionRangeSlider");

            ngModel.$render = function() {
                var options;
                if(isDouble) {
                    options = ngModel.$viewValue || {};
                } else {
                    options = {
                        from: ngModel.$viewValue
                    };
                }
                slider.update(options);
            };
            input.on('change', function() {
                ngModel.$setViewValue(isDouble ? {from: input.data("from"), to: input.data("to")} : input.data("from"));
            });
            element.on('mousedown', function() {
                if(!scope.$eval(attrs.ngDisabled)) {
                    $document.one('mouseup', function() {
                        scope.$emit('sliderSlideFinished');
                    });
                }
            });
            scope.$watch(attrs.ngDisabled, function(disabled) {
                slider.update({
                    disable: disabled
                });
            });
            scope.$on('$destroy', function() {
                slider.destroy();
            });
        }
    };
}]);

Rather than using element.on('mousedown' as on line 38, its probably best to use the built in callback functions:

 input.ionRangeSlider({
   grid:           scope.settings.grid,
   hide_min_max:   true,
   values:         scope.settings.values,
   prefix:         scope.settings.prefix,
   postfix:        scope.settings.postfix,
   from:           scope.settings.from,
   to:             scope.settings.to,
   min:            scope.settings.min,
   max:            scope.settings.max,
   step:           scope.settings.step,
   grid_num:       scope.settings.gridnum,
   type:           scope.settings.sliderType,
   force_edges:    true,
   onChange: function() {
       ngModel.$setViewValue(isDouble ? {from: input.data("from"), to: input.data("to")} : input.data("from"));
   },
   onFinish: function() {
      scope.$emit('selectorControlChanged');
   }
});