We leave css:light, text:light, id:light, and similar to opt-out from the shadow dom piercing. The notable exception is xpath that is always light.
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Selector engines
Playwright supports multiple selector engines used to query elements in the web page.
Selector can be used to obtain ElementHandle
(see page.$() for example) or shortcut element operations to avoid intermediate handle (see page.click() for example).
Selector syntax
Selector is a string that consists of one or more clauses separated by >>
token, e.g. clause1 >> clause2 >> clause3
. When multiple clauses are present, next one is queried relative to the previous one's result.
Each clause contains a selector engine name and selector body, e.g. engine=body
. Here engine
is one of the supported engines (e.g. css
or a custom one). Selector body
follows the format of the particular engine, e.g. for css
engine it should be a css selector. Body format is assumed to ignore leading and trailing whitespaces, so that extra whitespace can be added for readability. If selector engine needs to include >>
in the body, it should be escaped inside a string to not be confused with clause separator, e.g. text="some >> text"
.
For example,
css=article >> css=.bar > .baz >> css=span[attr=value]
is equivalent to
document
.querySelector('article')
.querySelector('.bar > .baz')
.querySelector('span[attr=value]')
For convenience, selectors in the wrong format are heuristically converted to the right format:
- Selector starting with
//
is assumed to bexpath=selector
. Example:page.click('//html')
is converted topage.click('xpath=//html')
. - Selector starting with
"
is assumed to betext=selector
. Example:page.click('"foo"')
is converted topage.click('text="foo"')
. - Otherwise, selector is assumed to be
css=selector
. Example:page.click('div')
is converted topage.click('css=div')
.
Examples
// queries 'div' css selector
const handle = await page.$('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.$('css=span');
Built-in selector engines
css and css:light
css
is a default engine - any malformed selector not starting with //
nor with "
is assumed to be a css selector. For example, Playwright converts page.$('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 incovenient 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 twodiv
elements that are direct children of thearticle
. "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-domdiv
elements do not contain aspan
."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 ofarticle
"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.$('xpath=//html/body')
.
Note that xpath
does not pierce shadow roots.
text and text:light
Text engine finds an element that contains a text node with the passed text. For example, page.click('text=Login')
clicks on a login button, and page.waitForSelector('"lazy loaded text")
waits for the "lazy loaded text"
to appear in the page.
- By default, the match is case-insensitive, ignores leading/trailing whitespace and searches for a substring. This means
text= Login
matches<button>Button loGIN (click me)</button>
. - Text body can be escaped with double quotes for precise matching, insisting on exact match, including specified whitespace and case. This means
text="Login "
will only match<button>Login </button>
with exactly one space after "Login". - Text body can also be a JavaScript-like regex wrapped in
/
symbols. This meanstext=/^\\s*Login$/i
will match<button> loGIN</button>
with any number of spaces before "Login" and no spaces after. - Input elements of the type
button
andsubmit
are rendered with their value as text, and text engine finds them. For example,text=Login
matches<input type=button value="Login">
.
Malformed selector starting with "
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 atrribute 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"]
.
Custom selector engines
Playwright supports custom selector engines, registered with selectors.register(name, script[, options]).
Selector engine should have the following properties:
create
function to create a relative selector fromroot
(root is either aDocument
,ShadowRoot
orElement
) to atarget
element.query
function to query first element matchingselector
relative to theroot
.queryAll
function to query all elements matchingselector
relative to theroot
.
By default the engine is run directly in the frame's JavaScript context and, for example, can call an application-defined function. To isolate the engine from any JavaScript in the frame, but leave access to the DOM, resgister the engine with {contentScript: true}
option. Content script engine is safer because it is protected from any tampering with the global objects, for example altering Node.prototype
methods. All built-in selector engines run as content scripts. Note that running as a content script is not guaranteed when the engine is used together with other custom engines.
An example of registering selector engine that queries elements based on a tag name:
// Must be a function that evaluates to a selector engine instance.
const createTagNameEngine = () => ({
// Creates a selector that matches given target when queried at the root.
// Can return undefined if unable to create one.
create(root, target) {
return root.querySelector(target.tagName) === target ? target.tagName : undefined;
},
// Returns the first element matching given selector in the root's subtree.
query(root, selector) {
return root.querySelector(selector);
},
// Returns all elements matching given selector in the root's subtree.
queryAll(root, selector) {
return Array.from(root.querySelectorAll(selector));
}
});
// Register the engine. Selectors will be prefixed with "tag=".
await selectors.register('tag', createTagNameEngine);
// Now we can use 'tag=' selectors.
const button = await page.$('tag=button');
// We can combine it with other selector engines using `>>` combinator.
await page.click('tag=div >> span >> "Click me"');
// We can use it in any methods supporting selectors.
const buttonCount = await page.$$eval('tag=button', buttons => buttons.length);