4b5b0c7d79
Demonstrates MCP App SDK usage with vanilla JavaScript (no framework), providing parity with the existing basic-server-react example. 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude <noreply@anthropic.com>
56 lines
2 KiB
Markdown
56 lines
2 KiB
Markdown
# Example: Basic Server (Vanilla JS)
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An MCP App example with a vanilla JavaScript UI (no framework).
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> [!TIP]
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> Looking for a React-based example? See [`basic-server-react`](https://github.com/modelcontextprotocol/ext-apps/tree/main/examples/basic-server-react)!
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## Overview
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- Tool registration with a linked UI resource
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- Vanilla JS UI using the [`App`](https://modelcontextprotocol.github.io/ext-apps/api/classes/app.App.html) class directly
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- App communication APIs: [`callServerTool`](https://modelcontextprotocol.github.io/ext-apps/api/classes/app.App.html#callservertool), [`sendMessage`](https://modelcontextprotocol.github.io/ext-apps/api/classes/app.App.html#sendmessage), [`sendLog`](https://modelcontextprotocol.github.io/ext-apps/api/classes/app.App.html#sendlog), [`sendOpenLink`](https://modelcontextprotocol.github.io/ext-apps/api/classes/app.App.html#sendopenlink)
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## Key Files
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- [`server.ts`](server.ts) - MCP server with tool and resource registration
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- [`mcp-app.html`](mcp-app.html) / [`src/mcp-app.ts`](src/mcp-app.ts) - Vanilla JS UI using `App` class
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## Getting Started
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```bash
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npm install
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npm run dev
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```
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## How It Works
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1. The server registers a `get-time` tool with metadata linking it to a UI HTML resource (`ui://get-time/mcp-app.html`).
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2. When the tool is invoked, the Host renders the UI from the resource.
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3. The UI uses the MCP App SDK API to communicate with the host and call server tools.
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## Vanilla JS Pattern
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```typescript
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import { App, PostMessageTransport } from "@modelcontextprotocol/ext-apps";
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// Get element references from static HTML
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const button = document.getElementById("my-button")!;
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// Create app instance
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const app = new App({ name: "My App", version: "1.0.0" });
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// Register handlers BEFORE connecting
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app.ontoolresult = (result) => {
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/* handle result */
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};
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app.onerror = console.error;
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// Add event listeners
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button.addEventListener("click", () => {
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/* ... */
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});
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// Connect to host
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app.connect(new PostMessageTransport(window.parent));
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```
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