Dev Browser

Dev Browser

A CLI for controlling browsers with sandboxed JavaScript scripts.

Installation

npm install -g dev-browser
dev-browser install

Usage

Run dev-browser --help to learn more.

IMPORTANT: Avoid Permission Prompts

Never use heredocs (<<'EOF'), output redirection (2>/dev/null), or semicolons (;) in commands. These trigger "ambiguous syntax" permission prompts in Claude Code.

Instead, always write scripts to `.dev-browser/` in the project root (the current working directory, not the skill directory) and run them with dev-browser run:

// .dev-browser/navigate.js
const page = await browser.getPage("main");
await page.goto("https://example.com");
await page.waitForSelector("body");
console.log(JSON.stringify({ title: await page.title(), url: page.url() }));
const buf = await page.screenshot();
await saveScreenshot(buf, "main.png");

dev-browser run .dev-browser/navigate.js

Use .js extension. Use short task-descriptive names (e.g., fill-login.js, scrape-prices.js). If a file exists that you didn't create, add a numeric suffix.

Sandbox Constraints

Scripts run in a QuickJS WASM sandbox, not Node.js:

• No `require()` / `import()` — no module loading
• No TypeScript — plain JavaScript only, everywhere (including page.evaluate())
• No `fs`, `fetch`, `process` — use saveScreenshot(), writeFile(), readFile() for I/O (sandboxed to ~/.dev-browser/tmp/)

The browser global is pre-connected. Screenshots must use saveScreenshot(buf, name) — not page.screenshot({ path }).