On Windows 10 with Puppeteer v10.2 and Node 8.2.1, calling page.evaluate with a passed callback results in a ‘not a function’ error. Example code:
let callbackAction = () => { console.log('Log entry'); };
const outcome = await page.evaluate(param => { param(); }, callbackAction);
hey, page.evaluate runs in the browser context so you cant pass around funcs from node. try using page.exposeFunction or just inclde the logic inside the eval call.
I encountered a similar problem when developing web scraping solutions with Puppeteer. The key is to understand that page.evaluate executes code in the browser environment where only serializable data can be transferred. Function definitions from Node.js are not carried over. In my experience, either wrapping the logic entirely within the evaluate call or utilizing page.exposeFunction to define callbacks within the browser context proves more effective. This practice not only resolves the error but also simplifies debugging and maintenance when managing browser-executed logic.
In my experience with Puppeteer, the function conversion issue is a common pitfall when attempting to pass Node.js functions to the browser context. The core problem is that page.evaluate operates in the browser environment and only accepts serializable data. When you try to pass a callback function directly, it doesn’t get transmitted correctly, leading to the error you observed. A viable solution is to incorporate the functionality within the evaluate call itself or expose the necessary functions to the web page using page.exposeFunction. This approach not only fixes the problem but also clarifies the separation between environments.
hey, i fixed it by writing the function straight in the eval block. you cant pass node funcs to the broswer, they just dont serialize. experimenting with page.exposeFunction was also a lifesaver for me