playwright/docs/navigations.md
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docs: update navigation and loading page (#3655)
* docs: update navigation and loading doc

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Navigations

Playwright can navigate to URLs and handle navigations caused by page interactions. This guide covers common scenarios to wait for page navigations and loading to complete.

Navigation lifecycle

Playwright splits the process of showing a new document in a page into navigation and loading.

Navigations can be initiated by changing the page URL or by interacting with the page (e.g., clicking a link). Navigation ends when response headers have been parsed and session history is updated. The navigation intent may be canceled, for example, on hitting an unresolved DNS address or transformed into a file download. Only after the navigation succeeds, page starts loading the document.

Loading covers getting the remaining response body over the network, parsing, executing the scripts and firing load events:

  • page.url() is set to the new url
  • document content is loaded over network and parsed
  • domcontentloaded event is fired
  • page executes some scripts and loads resources like stylesheets and images
  • load event is fired
  • page executes dynamically loaded scripts
  • networkidle is fired when no new network requests are made for 500 ms

Scenarios initiated by browser UI

Navigations can be initiated by changing the URL bar, reloading the page or going back or forward in session history.

Auto-wait

Navigating to a URL auto-waits for the page to fire the load event. If the page does a client-side redirect before load, page.goto will auto-wait for the redirected page to fire the load event.

// Navigate the page
await page.goto('https://example.com');

Custom wait

Override the default behavior to wait until a specific event, like networkidle.

// Navigate and wait until network is idle
await page.goto('https://example.com', { waitUntil: 'networkidle' });

Wait for element

In lazy-loaded pages, it can be useful to wait until an element is visible with page.waitForSelector. Alternatively, page interactions like page.click auto-wait for elements.

// Navigate and wait for element
await page.goto('https://example.com');
await page.waitForSelector('text=Example Domain');

// Navigate and click element
// Click will auto-wait for the element
await page.goto('https://example.com');
await page.click('text=Example Domain');

API reference

Scenarios initiated by page interaction

In the scenarios below, page.click initiates a navigation and then waits for the navigation to complete.

Auto-wait

By default, page.click will wait for the navigation step to complete. This can be combined with a page interaction on the navigated page which would auto-wait for an element.

// Click will auto-wait for navigation to complete
await page.click('text=Login');
// Fill will auto-wait for element on navigated page
await page.fill('#username', 'John Doe');

Custom wait

page.click can be combined with page.waitForLoadState to wait for a loading event.

await page.click('button'); // Click triggers navigation
await page.waitForLoadState('networkidle'); // This resolves after 'networkidle'

Wait for element

In lazy-loaded pages, it can be useful to wait until an element is visible with page.waitForSelector. Alternatively, page interactions like page.click auto-wait for elements.

// Click triggers navigation
await page.click('text=Login');
 // Click will auto-wait for the element
await page.waitForSelector('#username', 'John Doe');

// Click triggers navigation
await page.click('text=Login');
 // Fill will auto-wait for element
await page.fill('#username', 'John Doe');

Asynchronous navigation

Clicking an element could trigger asychronous processing before initiating the navigation. In these cases, it is recommended to explicitly call page.waitForNavigation. For example:

  • Navigation is triggered from a setTimeout
  • Page waits for network requests before navigation
await Promise.all([
  page.click('a'), // Triggers a navigation after a timeout
  page.waitForNavigation(), // Waits for the next navigation
]);

The Promise.all pattern prevents a race condition between page.click and page.waitForNavigation when navigation happens quickly.

Multiple navigations

Clicking an element could trigger multiple navigations. In these cases, it is recommended to explicitly page.waitForNavigation to a specific url. For example:

  • Client-side redirects issued after the load event
  • Multiple pushes to history state
await Promise.all([
  page.waitForNavigation({ url: '**/login' }),
  page.click('a'), // Triggers a navigation with a script redirect
]);

The Promise.all pattern prevents a race condition between page.click and page.waitForNavigation when navigation happens quickly.

Loading a popup

When popup is opened, explicitly calling page.waitForLoadState ensures that popup is loaded to the desired state.

const [ popup ] = await Promise.all([
  page.waitForEvent('popup'),
  page.click('a[target="_blank"]'),  // Opens popup
]);
await popup.waitForLoadState('load');

API reference

Advanced patterns

For pages that have complicated loading patterns, page.waitForFunction is a powerful and extensible approach to define a custom wait criteria.

await page.goto('http://example.com');
await page.waitForFunction(() => window.amILoadedYet());
// Ready to take a screenshot, according to the page itself.
await page.screenshot();

API reference