1.9 KiB
1.9 KiB
Home > puppeteer > Page > evaluate
Page.evaluate() method
Signature:
evaluate<T extends EvaluateFn>(pageFunction: T, ...args: SerializableOrJSHandle[]): Promise<UnwrapPromiseLike<EvaluateFnReturnType<T>>>;
Parameters
| Parameter | Type | Description |
|---|---|---|
| pageFunction | T | a function that is run within the page |
| args | SerializableOrJSHandle[] | arguments to be passed to the pageFunction |
Returns:
Promise<UnwrapPromiseLike<EvaluateFnReturnType<T>>>
the return value of pageFunction.
Remarks
Evaluates a function in the page's context and returns the result.
If the function passed to page.evaluteHandle returns a Promise, the function will wait for the promise to resolve and return its value.
Example 1
const result = await frame.evaluate(() => {
return Promise.resolve(8 * 7);
});
console.log(result); // prints "56"
You can pass a string instead of a function (although functions are recommended as they are easier to debug and use with TypeScript):
Example 2
const aHandle = await page.evaluate('1 + 2');
To get the best TypeScript experience, you should pass in as the generic the type of pageFunction:
const aHandle = await page.evaluate<() => number>(() => 2);
Example 3
ElementHandle instances (including JSHandles) can be passed as arguments to the pageFunction:
const bodyHandle = await page.$('body');
const html = await page.evaluate(body => body.innerHTML, bodyHandle);
await bodyHandle.dispose();