These commands download the Playwright package and install browser binaries for Chromium, Firefox and WebKit. To modify this behavior see [installation parameters](./browsers.md#installing-browsers).
## Usage
Once installed, you can `import` Playwright in a Python script, and launch any of the 3 browsers (`chromium`, `firefox` and `webkit`).
```py
from playwright.sync_api import sync_playwright
with sync_playwright() as p:
browser = p.chromium.launch()
page = browser.new_page()
page.goto("http://playwright.dev")
print(page.title())
browser.close()
```
Playwright supports two variations of the API: synchronous and asynchronous. If your modern project uses [asyncio](https://docs.python.org/3/library/asyncio.html), you should use async API:
```py
import asyncio
from playwright.async_api import async_playwright
async def main():
async with async_playwright() as p:
browser = await p.chromium.launch()
page = await browser.new_page()
await page.goto("http://playwright.dev")
print(await page.title())
await browser.close()
asyncio.run(main())
```
## First script
In our first script, we will navigate to `whatsmyuseragent.org` and take a screenshot in WebKit.
```py
from playwright.sync_api import sync_playwright
with sync_playwright() as p:
browser = p.webkit.launch()
page = browser.new_page()
page.goto("http://whatsmyuseragent.org/")
page.screenshot(path="example.png")
browser.close()
```
By default, Playwright runs the browsers in headless mode. To see the browser UI, pass the `headless=False` flag while launching the browser. You can also use [`option: slowMo`] to slow down execution. Learn more in the debugging tools [section](./debug.md).
```py
firefox.launch(headless=False, slow_mo=50)
```
## Interactive mode (REPL)
You can launch the interactive python REPL:
```bash
python
```
and then launch Playwright within it for quick experimentation:
```py
>>> from playwright.sync_api import sync_playwright
>>> playwright = sync_playwright().start()
# Use playwright.chromium, playwright.firefox or playwright.webkit
# Pass headless=False to launch() to see the browser UI
>>> browser = playwright.chromium.launch()
>>> page = browser.new_page()
>>> page.goto("http://whatsmyuseragent.org/")
>>> page.screenshot(path="example.png")
>>> browser.close()
>>> playwright.stop()
```
Async REPL such as `asyncio` REPL:
```bash
python -m asyncio
```
```py
>>> from playwright.async_api import async_playwright
Bundling the browsers with the executables will generate bigger binaries.
It is recommended to only bundle the browsers you use.
:::
## Known issues
### `time.sleep()` leads to outdated state
Most likely you don't need to wait manually, since Playwright has [auto-waiting](./actionability.md). If you still rely on it, you should use `page.wait_for_timeout(5000)` instead of `time.sleep(5)` and it is better to not wait for a timeout at all, but sometimes it is useful for debugging. In these cases, use our wait (`wait_for_timeout`) method instead of the `time` module. This is because we internally rely on asynchronous operations and when using `time.sleep(5)` they can't get processed correctly.
### incompatible with `SelectorEventLoop` of `asyncio` on Windows
Playwright runs the driver in a subprocess, so it requires `ProactorEventLoop` of `asyncio` on Windows because `SelectorEventLoop` does not supports async subprocesses.
On Windows Python 3.7, Playwright sets the default event loop to `ProactorEventLoop` as it is default on Python 3.8+.
### Threading
Playwright's API is not thread-safe. If you are using Playwright in a multi-threaded environment, you should create a playwright instance per thread. See [threading issue](https://github.com/microsoft/playwright-python/issues/623) for more details.
