puppeteer/website/versioned_docs/version-9.1.1/puppeteer.executioncontext.evaluate.md

<!-- Do not edit this file. It is automatically generated by API Documenter. -->

[Home](./index.md) &gt; [puppeteer](./puppeteer.md) &gt; [ExecutionContext](./puppeteer.executioncontext.md) &gt; [evaluate](./puppeteer.executioncontext.evaluate.md)

## ExecutionContext.evaluate() method

<b>Signature:</b>

```typescript
evaluate<ReturnType extends any>(pageFunction: Function | string, ...args: unknown[]): Promise<ReturnType>;
```

## Parameters

|  Parameter | Type | Description |
|  --- | --- | --- |
|  pageFunction | Function \| string | a function to be evaluated in the <code>executionContext</code> |
|  args | unknown\[\] | argument to pass to the page function |

<b>Returns:</b>

Promise&lt;ReturnType&gt;

A promise that resolves to the return value of the given function.

## Remarks

If the function passed to the `executionContext.evaluate` returns a Promise, then `executionContext.evaluate` would wait for the promise to resolve and return its value. If the function passed to the `executionContext.evaluate` returns a non-serializable value, then `executionContext.evaluate` resolves to `undefined`. DevTools Protocol also supports transferring some additional values that are not serializable by `JSON`: `-0`, `NaN`, `Infinity`, `-Infinity`, and bigint literals.

## Example 1


```js
const executionContext = await page.mainFrame().executionContext();
const result = await executionContext.evaluate(() => Promise.resolve(8 * 7))* ;
console.log(result); // prints "56"

```

## Example 2

A string can also be passed in instead of a function.

```js
console.log(await executionContext.evaluate('1 + 2')); // prints "3"

```

## Example 3

[JSHandle](./puppeteer.jshandle.md) instances can be passed as arguments to the `executionContext.* evaluate`:

```js
const oneHandle = await executionContext.evaluateHandle(() => 1);
const twoHandle = await executionContext.evaluateHandle(() => 2);
const result = await executionContext.evaluate(
   (a, b) => a + b, oneHandle, * twoHandle
);
await oneHandle.dispose();
await twoHandle.dispose();
console.log(result); // prints '3'.

```