paramName
( optional Type array of paramType )
Undocumented.
Description of this parameter from the json schema.
Browser Actions

Use browser actions to put icons in the main Google Chrome toolbar, to the right of the address bar. In addition to its icon, a browser action can also have a tooltip, a badge, and a popup.

In the following figure, the multicolored square to the right of the address bar is the icon for a browser action. A popup is below the icon.

If you want to create an icon that isn't always visible, use a page action instead of a browser action.

[PENDING: We should show tooltips and badges, as well.]

Manifest

Register your browser action in the extension manifest like this: 

"browser_action": {
  "default_title": "Google Mail",      // optional; shown in tooltip
  "default_icon": "images/icon19.png", // optional
  "popup": "popup.html"                // optional
}

Note: Even if you don't include any of the values, you must include an empty browser_action entry in the manifest so that the system reserves space for your browser action in the toolbar.

Parts of the UI

A browser action must have an icon. It can also have a tooltip, a badge, and a popup.

Icon

Browser action icons can be up to 19 pixels wide and high. Larger icons are resized to fit, but for best results, use a 19-pixel square icon.

You can set the icon in two ways: using a static image or using the HTML5 canvas element. Using static images is easier for simple applications, but you can create more dynamic UIs — such as smooth animation — using the canvas element.

Static images can be in any format WebKit can display, including BMP, GIF, ICO, JPEG, or PNG.

To set the icon, use the default_icon field of browser_action in the manifest, or call the setIcon() method.

Tooltip

To set the tooltip, use the default_title field of browser_action in the manifest, or call the setTitle() method.

Badge

Browser actions can optionally display a badge — a bit of text that is layered over the icon. Badges make it easy to update the browser action to display a small amount of information about the state of the extension.

Because the badge has limited space, it should have 4 characters or less.

Set the text and color of the badge using setBadgeText() and setBadgeBackgroundColor(), respectively. [PENDING: if you have a color but no text, will anything display?]

Popup

If a browser action has a popup, the popup appears when the user clicks the icon. The popup can contain any HTML contents that you like, and it's automatically sized to fit its contents.

To add a popup to your browser action, create an HTML file with the popup's contents. Then specify the HTML file in the manifest, using the popup field of browser_action.

Tips

For the best visual impact, follow these guidelines:

  • Do use browser actions for features that make sense on most pages.
  • Don't use browser actions for features that make sense for only a few pages. Use page actions instead.
  • Do use big, colorful icons that make the most of the 19x19-pixel space. Browser action icons should seem a little bigger and heavier than page action icons.
  • Don't attempt to mimic Google Chrome's monochrome "wrench" and "page" icons. That doesn't work well with themes, and anyway, extensions should stand out a little.
  • Do use alpha transparency to add soft edges to your icon. Because many people use themes, your icon should look nice on a variety of background colors.
  • Don't constantly animate your icon. That's just annoying.

API reference: chrome.browserAction

Methods

setBadgeBackgroundColor

void chrome.browserAction.setBadgeBackgroundColor(, object details)

Sets the background color for the badge.

Parameters

details
( Type array of object )
Undocumented.
Description of this parameter from the json schema.
color
( Type array of Type array of integer paramType )
An array of four integers in the range [0,255] that make up the RGBA color of the badge. For example, opaque red is [255, 0, 0, 255].
tabId
( optional Type array of integer )
Limits the change to when a particular tab is selected. Automatically resets when the tab is closed.

Returns

Callback function

If you specify the callback parameter, it should specify a function that looks like this: 

function(Type param1, Type param2) {...});

setBadgeText

void chrome.browserAction.setBadgeText(, object details)

Sets the badge text for the browser action. The badge is displayed on top of the icon.

Parameters

details
( Type array of object )
Undocumented.
Description of this parameter from the json schema.
text
( Type array of string )
Any number of characters can be passed, but only about four can fit in the space.
tabId
( optional Type array of integer )
Limits the change to when a particular tab is selected. Automatically resets when the tab is closed.

Returns

Callback function

If you specify the callback parameter, it should specify a function that looks like this: 

function(Type param1, Type param2) {...});

setIcon

void chrome.browserAction.setIcon(, object details)

Sets the icon for the browser action. The icon can be specified either as the path to an image file or as the pixel data from a canvas element. Either the path or the imageData property must be specified.

Parameters

details
( Type array of object )
Undocumented.
Description of this parameter from the json schema.
imageData
( optional Type array of any )
Pixel data for an image. Must be an ImageData object (for example, from a canvas element).
path
( optional Type array of string )
Relative path to an image in the extension to show in the browser action.
tabId
( optional Type array of integer )
Limits the change to when a particular tab is selected. Automatically resets when the tab is closed.

Returns

Callback function

If you specify the callback parameter, it should specify a function that looks like this: 

function(Type param1, Type param2) {...});

setTitle

void chrome.browserAction.setTitle(, object details)

Sets the title of the browser action. This shows up in the tooltip.

Parameters

details
( Type array of object )
Undocumented.
Description of this parameter from the json schema.
title
( Type array of string )
The string the browser action should display when moused over.
tabId
( optional Type array of integer )
Limits the change to when a particular tab is selected. Automatically resets when the tab is closed.

Returns

Callback function

If you specify the callback parameter, it should specify a function that looks like this: 

function(Type param1, Type param2) {...});

Events

onClicked

chrome.browserAction.onClicked.addListener(function(Tab tab) {...});

Fired when a browser action icon is clicked.

Parameters

tab
( Tab array of paramType )
Undocumented.
Description of this parameter from the json schema.