puppeteer/docs/api/puppeteer.webworker.evaluate.md

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2022-07-05 13:41:43 +00:00
---
sidebar_label: WebWorker.evaluate
---
# WebWorker.evaluate() method
If the function passed to the `worker.evaluate` returns a Promise, then `worker.evaluate` would wait for the promise to resolve and return its value. If the function passed to the `worker.evaluate` returns a non-serializable value, then `worker.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. Shortcut for `await worker.executionContext()).evaluate(pageFunction, ...args)`.
#### Signature:
2022-07-05 13:41:43 +00:00
```typescript
class WebWorker {
evaluate<
Params extends unknown[],
Func extends EvaluateFunc<Params> = EvaluateFunc<Params>
>(
pageFunction: Func | string,
...args: Params
): Promise<Awaited<ReturnType<Func>>>;
}
```
## Parameters
| Parameter | Type | Description |
| ------------ | -------------- | ----------------------------------------------- |
| pageFunction | Func \| string | Function to be evaluated in the worker context. |
| args | Params | Arguments to pass to <code>pageFunction</code>. |
**Returns:**
Promise&lt;Awaited&lt;ReturnType&lt;Func&gt;&gt;&gt;
Promise which resolves to the return value of `pageFunction`.