playwright/docs/selectors.md
Dmitry Gozman f9f5fd03b0
feat(selectors): allow to capture intermediate result (#1978)
This introduces the `*name=body` syntax to capture intermediate result.
For example, `*css=section >> "Title"` will capture a section that contains "Title".
2020-04-27 10:14:09 -07:00

7.9 KiB

Selector engines

Playwright supports multiple selector engines used to query elements in the web page.

Selector can be used to obtain ElementHandle (see page.$() for example) or shortcut element operations to avoid intermediate handle (see page.click() for example).

Selector syntax

Selector is a string that consists of one or more clauses separated by >> token, e.g. clause1 >> clause2 >> clause3. When multiple clauses are present, next one is queried relative to the previous one's result.

Each clause contains a selector engine name and selector body, e.g. engine=body. Here engine is one of the supported engines (e.g. css or a custom one). Selector body follows the format of the particular engine, e.g. for css engine it should be a css selector. Body format is assumed to ignore leading and trailing white spaces, so that extra whitespace can be added for readability. If selector engine needs to include >> in the body, it should be escaped inside a string to not be confused with clause separator, e.g. text="some >> text".

For example,

css=article >> css=.bar > .baz >> css=span[attr=value]

is equivalent to

document
  .querySelector('article')
  .querySelector('.bar > .baz')
  .querySelector('span[attr=value]')

Selector engine name can be prefixed with * to capture element that matches the particular clause instead of the last one. For example, css=article >> text=Hello captures the element with the text Hello, and *css=article >> text=Hello (note the *) captures the article element that contains some element with the text Hello.

For convenience, selectors in the wrong format are heuristically converted to the right format:

  • Selector starting with // is assumed to be xpath=selector. Example: page.click('//html') is converted to page.click('xpath=//html').
  • Selector surrounded with quotes (either " or ') is assumed to be text=selector. Example: page.click('"foo"') is converted to page.click('text="foo"').
  • Otherwise, selector is assumed to be css=selector. Example: page.click('div') is converted to page.click('css=div').

Examples

// queries 'div' css selector
const handle = await page.$('css=div');

// queries '//html/body/div' xpath selector
const handle = await page.$('xpath=//html/body/div');

// queries '"foo"' text selector
const handle = await page.$('text="foo"');

// queries 'span' css selector inside the result of '//html/body/div' xpath selector
const handle = await page.$('xpath=//html/body/div >> css=span');

// converted to 'css=div'
const handle = await page.$('div');

// converted to 'xpath=//html/body/div'
const handle = await page.$('//html/body/div');

// converted to 'text="foo"'
const handle = await page.$('"foo"');

// queries 'span' css selector inside the div handle
const handle = await divHandle.$('css=span');

Built-in selector engines

css and css:light

css is a default engine - any malformed selector not starting with // nor surrounded with quotes is assumed to be a css selector. For example, Playwright converts page.$('span > button') to page.$('css=span > button').

css:light engine is equivalent to Document.querySelector and behaves according to the CSS spec. However, it does not pierce shadow roots, which may be inconvenient when working with Shadow DOM and Web Components. For that reason, css engine pierces shadow roots. More specifically, every Descendant combinator pierces an arbitrary number of open shadow roots, including the implicit descendant combinator at the start of the selector.

css engine first searches for elements in the light dom in the iteration order, and then recursively inside open shadow roots in the iteration order. It does not search inside closed shadow roots or iframes.

Examples

<article>
  <div>In the light dom</div>
  <div slot='myslot'>In the light dom, but goes into the shadow slot</div>
  <open mode shadow root>
    <div class='in-the-shadow'>
      <span class='content'>
        In the shadow dom
        <open mode shadow root>
          <li id='target'>Deep in the shadow</li>
        </open mode shadow root>
      </span>
    </div>
    <slot name='myslot'></slot>
  </open mode shadow root>
</article>

Note that <open mode shadow root> is not an html element, but rather a shadow root created with element.attachShadow({mode: 'open'}).

  • Both "css=article div" and "css:light=article div" match the first <div>In the light dom</div>.
  • Both "css=article > div" and "css:light=article > div" match two div elements that are direct children of the article.
  • "css=article .in-the-shadow" matches the <div class='in-the-shadow'>, piercing the shadow root, while "css:light=article .in-the-shadow" does not match anything.
  • "css:light=article div > span" does not match anything, because both light-dom div elements do not contain a span.
  • "css=article div > span" matches the <span class='content'>, piercing the shadow root.
  • "css=article > .in-the-shadow" does not match anything, because <div class='in-the-shadow'> is not a direct child of article
  • "css:light=article > .in-the-shadow" does not match anything.
  • "css=article li#target" matches the <li id='target'>Deep in the shadow</li>, piercing two shadow roots.

xpath

XPath engine is equivalent to Document.evaluate. Example: xpath=//html/body.

Malformed selector starting with // is assumed to be an xpath selector. For example, Playwright converts page.$('//html/body') to page.$('xpath=//html/body').

Note that xpath does not pierce shadow roots.

text and text:light

Text engine finds an element that contains a text node with the passed text. For example, page.click('text=Login') clicks on a login button, and page.waitForSelector('"lazy loaded text") waits for the "lazy loaded text" to appear in the page.

  • By default, the match is case-insensitive, ignores leading/trailing whitespace and searches for a substring. This means text= Login matches <button>Button loGIN (click me)</button>.
  • Text body can be escaped with single or double quotes for precise matching, insisting on exact match, including specified whitespace and case. This means text="Login " will only match <button>Login </button> with exactly one space after "Login". Quoted text follows the usual escaping rules, e.g. use \" to escape double quote in a double-quoted string: text="foo\"bar".
  • Text body can also be a JavaScript-like regex wrapped in / symbols. This means text=/^\\s*Login$/i will match <button> loGIN</button> with any number of spaces before "Login" and no spaces after.
  • Input elements of the type button and submit are rendered with their value as text, and text engine finds them. For example, text=Login matches <input type=button value="Login">.

Malformed selector surrounded with quotes (either " or ') is assumed to be a text selector. For example, Playwright converts page.click('"Login"') to page.click('text="Login"').

text engine open pierces shadow roots similarly to css, while text:light does not. Text engine first searches for elements in the light dom in the iteration order, and then recursively inside open shadow roots in the iteration order. It does not search inside closed shadow roots or iframes.

id, data-testid, data-test-id, data-test and their :light counterparts

Attribute engines are selecting based on the corresponding attribute value. For example: data-test-id=foo is equivalent to css=[data-test-id="foo"], and id:light=foo is equivalent to css:light=[id="foo"].