Fundamentals of Reliable Automation

Understanding Execution Context

The first part of mastering Playwright is understanding how it communicates with the browser. Unlike traditional tools like Selenium, Playwright uses the Chrome DevTools Protocol (CDP) to issue low-level commands directly to the browser. Let's break it down now.

Browser vs Context vs Page

A Browser instance is heavy. A Context is cheap. Always use browser contexts instead of launching new browsers between tests.

playwright-init.ts
const browser = await chromium.launch();
const context = await browser.newContext();
const page = await context.newPage();

Actionability Checks

Before Playwright executes any action on an element, it performs actionable checks. The element must be:

• Attached to the DOM
• Visible
• Stable, as in not animating or completed animation
• Receives Events, as in not obscured by other elements
• Enabled