コンテキストメニュー項目の追加

Browser extensions can add custom items to the context menu, which appears when you right-click on a web page.

These items let users perform quick actions related to what they clicked on, like saving an image, translating selected text, or triggering a custom search.

Before your extension can create context menu items, you need to declare the "contextMenus" permission in your manifest.json file.

This permission tells the browser your extension intends to interact with the context menu API.

The chrome.contextMenus API is how your background service worker interacts with context menus.

It provides methods to manage menu items:

• create(): To add a new menu item.
• update(): To change an existing item's properties.
• remove(): To delete a specific item.
• removeAll(): To clear all items added by your extension.

To create a context menu item, use chrome.contextMenus.create(). You must provide a unique id and a title.

This example adds a simple item named "My First Item" to the general page context menu.

Each context menu item needs a unique id. This ID helps you identify which item was clicked later.

The title is the text displayed in the menu. The contexts array specifies where the item should appear.

• id: A unique string identifier.
• title: The user-visible text for the menu item.
• contexts: An array of strings defining where the item shows up.

After creating an item, you'll want to run code when a user clicks it. Use chrome.contextMenus.onClicked.addListener() to listen for these clicks.

The listener receives an info object with details about the click, including the menuItemId, which helps you identify which item was activated.

The contexts property is powerful! It allows you to control exactly where your menu item appears.

Common context types include:

• "page": Right-click on any part of the page.
• "selection": Right-click on selected text.
• "link": Right-click on a hyperlink.
• "image": Right-click on an image.
• "video", "audio": For media elements.

Let's create an item that appears only when text is selected. When clicked, it will open a new tab to search that text on Google.

Notice the selectionText property in the info object when using the "selection" context.

You can dynamically change or remove context menu items after they've been created. This is useful for adapting to user preferences or page content.

• chrome.contextMenus.update(id, properties): Changes properties like title or contexts.
• chrome.contextMenus.remove(id): Deletes a specific item.
• chrome.contextMenus.removeAll(): Deletes all items added by your extension.

Consider the following manifest.json and background script for an extension.

Which statements about the context menu items created are true?

You've learned how to add custom context menu items to your browser extension!

• Declare "contextMenus" permission in manifest.json.
• Use chrome.contextMenus.create() in your background script.
• Specify id, title, and contexts for each item.
• Listen for clicks using chrome.contextMenus.onClicked.addListener().
• Contexts like "page", "selection", "link" allow precise targeting.

These skills enable you to add powerful, context-aware actions to your extension. Next, we'll explore integrating with the Omnibox!