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Opera Dragonfly Manual Karl / storage.markdown

Storage Inspector

The Storage Inspector in Opera Dragonfly is accessible from the Storage panel in the application toolbar. The Storage Inspector displays all the data that is stored by the site or application on the client side. This includes cookies and HTML5 Web Storage. For applications based on W3C Widgets (such as Opera Widgets and Opera’s extensions), data stored in Widget Preferences is also shown.


A cookie consists of name-value pairs and associated metadata. An HTTP server can use the Set-Cookie header to pass the pairs to the browser in the HTTP header response. When the user agent makes subsequent requests to the server, the user agent uses the metadata and other information to determine whether to return the name/value pairs in the Cookie header.

Note: Cookies were defined by HTTP State Management Mechanism (RFC 2965) but it is in the process of being obsoleted by HTTP State Management Mechanism.

The cookies panel lists all cookies set by the site being debugged: they are arranged in a table, sorted by domain and grouped by the host and path. Each row includes a column for each cookie attribute: name, value, expiry date etc.

<img src="img/cookies-list.png" alt="list of cookies" />

Types of cookies

There are various kinds of cookies. Opera Dragonfly provides a means to view and modify cookies as follows.

A session cookie, once set by the server, will be deleted at the end of the session (when the browser is closed or the session times out after a period of inactivity). These cookies are labelled with <q>session</q> in the <q>Expires</q> column.

A persistent cookie is not destroyed when the session ends. It lasts for the time period listed in the <q>Expires</q> column. The Expires column uses a human-friendly representation of the expiry date. Hovering over the expiry date will show the complete expiry date and time in a tooltip.

Session and persistent cookies can also be secure. A secure cookie is encrypted when sent to the browser using the HTTPS protocol. It is not transmitted when using HTTP. Secure cookies are labelled with a tick icon in the <q>Secure</q> column.

Session and persistent cookies can also be HTTPOnly. A HTTPOnly cookie can not be accessed by client-side scripting, which is designed to help against cross-site scripting attacks. HTTPOnly cookies are labelled with a tick icon in the <q>HTTPOnly</q> column.

Sorting and grouping cookies

Clicking on the headings of each column will sort the table in ascending/descending order by the column in question.

Cookies are grouped by their hosts and paths by default. It is possible to ungroup the cookies by selecting <q>No grouping</q> from the table header row’s context menu.

<img src="img/no-grouping.png" alt="ungrouping cookies" />

Selecting cookies

Clicking on a cookie's row will select it. It is possible to select multiple cookies by holding down the <kbd>Ctrl</kbd> (<kbd>⌘</kbd>) key while clicking on them.

A cookie can be added by selecting <q>Add cookie</q> from the context menu or by clicking on the <q>Add cookie</q> button. When the cookies are grouped, each domain has a <q>Add cookie</q> button, which pre-fills the domain field to that domain. When ungrouped, the button can be found at the bottom of the table, and the domain is pre-filled to the same domain as the previous cookie. The domain can be set to any valid domain, but it will not be shown if it doesn't match one of the listed domains. The cookie will be shown when inspecting the domain on which it was set.

<img src="img/adding-cookie.png" alt="Adding a new cookie" />

The expiry date can be selected using the provided calendar widget. Opera Dragonfly will automatically translate the date and time into a easily human-readable date. To set a session cookie, set the date to 1970-1-1 0:00 (the Unix epoch). This is a current limitation with the UI, which will be fixed in a future version.

Editing cookies

Cookies can be edited by double-clicking on the cookie row, or by selecting <q>Edit cookie</q> from the context menu, to bring up editable fields and then altering the text in each field. As with adding a cookie, editing a cookie to apply to a different domain will keep the cookie, but it will not show in the list as it will no longer apply to the current debugging context.

Deleting cookies

There are two options for deleting cookies. An individual cookie can be removed by selecting <q>Remove cookie</q> from the cookie row’s context menu. All cookies for a specific domain can be removed by selecting <q>Remove cookies of <var>domain name</var></q> from the context menu of any cookie that is set on that domain.

Web Storage

The Web Storage API defines persistent storage of data using key-value pairs in web clients. Web Storage can fulfill the same use cases as cookies, without many of the drawbacks such as increased storage space or the ability to access stored data for the same website across two different windows.

The Storage Inspector separates the two types of Web Storage into their own sub panels. Each entry is displayed in a key-value list.

<img src="img/local-storage.png" alt="local storage" />

Session Storage

Session Storage is somewhat similar to a session cookie in that it lasts for the lifetime of the session and is then destroyed. Data stored with Session Storage can be found in the Session Storage panel.

Local Storage

Local Storage is more like persistent cookies. The data stored with Local Storage is not destroyed unless the user deletes it through the browser UI, or for security reasons. Data stored with Local Storage can be found in the Local Storage panel.

Editing an entry

Local and Session Storage Values can be edited by double-clicking on the value column. After updating the value click on the <q>Apply</q> button. Pressing the <q>Cancel</q> button will revert the change. Note that the key can not be edited in Opera Dragonfly.

Deleting entries

An entry can be deleted by clicking on the <q>delete</q> icon at the end of the row. All entries can be deleted by pressing the <q>trash can</q> icon under the table.

Adding an entry

An entry can be added by clicking the <q>Add</q> button under the table. This will add an extra row at the end of the table where the key and value can be entered. Saving and canceling are handled in the same way as editing an entry.

Widget Preferences

<a href="http://www.w3.org/TR/widgets-apis/#the-preferences-attribute">Widget Preferences</a> use the same Storage interface as Web Storage, but they are specific to applications implementing the Widgets API. In the Opera browser, each widget or extension has its own storage area to store its preference data. The data in this storage area can be found via the Widget Preferences panel, which remains blank for websites and applications that do not implement the Widgets API.

Data in the Widget Preferences panel can be manipulated in the same way as Web Storage entries.

A note about the Web Storage and Widget Preferences panels: The UI for Local Storage, Session Storage, and Widget Preferences panels will be updated to use the same UI as the Cookies panel in a future version of Opera Dragonfly.