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Developer tools

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Opera includes several tools to aid Web developers, most importantly Opera Dragonfly, a tool that enables remote debugging of Web pages.

The developer console is a tool for analyzing and/or interactively modifying a Web page during development or debugging, while the source viewer is a simpler tool for examining the source code of a Web page, and making quick changes.

Opera Dragonfly

Note: to use Opera Dragonfly, JavaScript must be enabled.

Opera Dragonfly is a JavaScript application used to debug local and remote Web pages. To open it, select the menu item Tools > Advanced > Developer tools. The user interface contains three tabs:

Opera Dragonfly is still in development. For more information, see the following articles:

The developer console

Like the other JavaScript applications on Dev.Opera, the developer console can be dragged and dropped onto any Opera toolbar. When you open the developer console, a small window will appear on top of the Web page to be analyzed, with five tabs: DOM, JS, CSS, HTTP, and About.

Note: to use the JavaScript applications on Dev.Opera, pop-ups must be enabled.

The developer console opens in the DOM tab, with the list of nodes collapsed under "document". Click on the plus sign to expand the list. When you click on a node, the Web page will flash briefly to indicate the region associated with this node.

Alternatively, clicking anywhere on the Web page will open up a list of DOM nodes, with the node relevant to that region of the page highlighted. To find the relevant region, press and hold the Shift key while scanning the page with the mouse.

The following are key features of the DOM tab:

The developer console can be used to interactively modify a Web page. The "Remove" button in the DOM tab permits removal of nodes, but also any CSS property can be edited from within the CSS tab, after pressing the button "Show rules" for the appropriate style sheet. The result of the changes is displayed instantly, and can be exported for later use.

A more detailed discussion of the developer console can be found on Dev.Opera.

The source viewer

Opera includes a simpler tool for analyzing and modifying Web pages, the source viewer. If you want to have a look at the source code of the current Web page, go to View > Source, or press ⌘+F3, or Ctrl-click the page and select "Source".

The source viewer opens in a new tab on your tab bar, and has syntax highlighting to give you a better overview of the source. If you want to edit the page, you have two options:

  1. Save to cache and see your changes applied immediately by clicking "Apply changes", or pressing ⌘+R.
  2. Save to a location of your choice by clicking "Save", or pressing ⌘+S.

Note that if you are editing a locally saved document "Apply changes" will permanently save your changes.

If you prefer to use an external program for source viewing and editing, you can specify this in the programs preferences.