[Home](./index.md) > [puppeteer](./puppeteer.md) > [WebWorker](./puppeteer.webworker.md) > [evaluate](./puppeteer.webworker.evaluate.md) ## 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: ```typescript evaluate(pageFunction: Function | string, ...args: any[]): Promise; ``` ## Parameters | Parameter | Type | Description | | --- | --- | --- | | pageFunction | Function \| string | Function to be evaluated in the worker context. | | args | any\[\] | Arguments to pass to pageFunction. | Returns: Promise<ReturnType> Promise which resolves to the return value of `pageFunction`.