class: JSHandle

JSHandle represents an in-page JavaScript object. JSHandles can be created with the Page.evaluateHandle() method.

const windowHandle = await page.evaluateHandle(() => window);
// ...

JSHandle windowHandle = page.evaluateHandle("() => window");
// ...

window_handle = await page.evaluate_handle("window")
# ...

window_handle = page.evaluate_handle("window")
# ...

var windowHandle = await page.EvaluateHandleAsync("() => window");

JSHandle prevents the referenced JavaScript object being garbage collected unless the handle is exposed with JSHandle.dispose(). JSHandles are auto-disposed when their origin frame gets navigated or the parent context gets destroyed.

JSHandle instances can be used as an argument in Page.evalOnSelector(), Page.evaluate() and Page.evaluateHandle() methods.

method: JSHandle.asElement

Returns either null or the object handle itself, if the object handle is an instance of ElementHandle.

async method: JSHandle.dispose

The jsHandle.dispose method stops referencing the element handle.

async method: JSHandle.evaluate

Returns the return value of expression.

This method passes this handle as the first argument to expression.

If expression returns a Promise, then handle.evaluate would wait for the promise to resolve and return its value.

Usage

const tweetHandle = await page.$('.tweet .retweets');
expect(await tweetHandle.evaluate(node => node.innerText)).toBe('10 retweets');

ElementHandle tweetHandle = page.querySelector(".tweet .retweets");
assertEquals("10 retweets", tweetHandle.evaluate("node => node.innerText"));

tweet_handle = await page.query_selector(".tweet .retweets")
assert await tweet_handle.evaluate("node => node.innerText") == "10 retweets"

tweet_handle = page.query_selector(".tweet .retweets")
assert tweet_handle.evaluate("node => node.innerText") == "10 retweets"

var tweetHandle = await page.QuerySelectorAsync(".tweet .retweets");
Assert.AreEqual("10 retweets", await tweetHandle.EvaluateAsync("node => node.innerText"));

param: JSHandle.evaluate.expression = %%-evaluate-expression-%%

param: JSHandle.evaluate.expression = %%-js-evaluate-pagefunction-%%

param: JSHandle.evaluate.arg

arg ?<EvaluationArgument>

Optional argument to pass to expression.

async method: JSHandle.evaluateHandle

Returns the return value of expression as a JSHandle.

This method passes this handle as the first argument to expression.

The only difference between jsHandle.evaluate and jsHandle.evaluateHandle is that jsHandle.evaluateHandle returns JSHandle.

If the function passed to the jsHandle.evaluateHandle returns a Promise, then jsHandle.evaluateHandle would wait for the promise to resolve and return its value.

See Page.evaluateHandle() for more details.

param: JSHandle.evaluateHandle.expression = %%-evaluate-expression-%%

param: JSHandle.evaluateHandle.expression = %%-js-evaluate-pagefunction-%%

param: JSHandle.evaluateHandle.arg

arg ?<EvaluationArgument>

Optional argument to pass to expression.

async method: JSHandle.getProperties

The method returns a map with own property names as keys and JSHandle instances for the property values.

Usage

const handle = await page.evaluateHandle(() => ({ window, document }));
const properties = await handle.getProperties();
const windowHandle = properties.get('window');
const documentHandle = properties.get('document');
await handle.dispose();

JSHandle handle = page.evaluateHandle("() => ({ window, document })");
Map<String, JSHandle> properties = handle.getProperties();
JSHandle windowHandle = properties.get("window");
JSHandle documentHandle = properties.get("document");
handle.dispose();

handle = await page.evaluate_handle("({ window, document })")
properties = await handle.get_properties()
window_handle = properties.get("window")
document_handle = properties.get("document")
await handle.dispose()

handle = page.evaluate_handle("({ window, document })")
properties = handle.get_properties()
window_handle = properties.get("window")
document_handle = properties.get("document")
handle.dispose()

var handle = await page.EvaluateHandleAsync("() => ({ window, document }");
var properties = await handle.GetPropertiesAsync();
var windowHandle = properties["window"];
var documentHandle = properties["document"];
await handle.DisposeAsync();

async method: JSHandle.getProperty

Fetches a single property from the referenced object.

param: JSHandle.getProperty.propertyName

propertyName <string>

property to get

async method: JSHandle.jsonValue

Returns a JSON representation of the object. If the object has a toJSON function, it will not be called.

note

The method will return an empty JSON object if the referenced object is not stringifiable. It will throw an error if the object has circular references.

method: JSHandle.asElement​

async method: JSHandle.dispose​

async method: JSHandle.evaluate​

param: JSHandle.evaluate.expression = %%-evaluate-expression-%%​

param: JSHandle.evaluate.expression = %%-js-evaluate-pagefunction-%%​

param: JSHandle.evaluate.arg​

async method: JSHandle.evaluateHandle​

param: JSHandle.evaluateHandle.expression = %%-evaluate-expression-%%​

param: JSHandle.evaluateHandle.expression = %%-js-evaluate-pagefunction-%%​

param: JSHandle.evaluateHandle.arg​

async method: JSHandle.getProperties​

async method: JSHandle.getProperty​

param: JSHandle.getProperty.propertyName​

async method: JSHandle.jsonValue​