node.js - How do I pass a variable to a callback in puppeteer's $eval?

Question

The following code doesn't work due to a ReferenceError when trying to access uid. I understand that the eval code is running inside the browser's context and thus doesn't have access to this variable, but I don't know how to pass the variable's value regardless:

var uid = '[email protected]';
await page.$eval('#uid', el => el.value = uid);

Answer 1

The third argument of page.$eval() passes in arguments, so you would do:

await page.$eval('#uid', (el, _uid) => el.value = _uid, uid);

page.$eval() docs as of Puppeteer 1.3.0:

page.$eval(selector, pageFunction[, ...args])

• selector <string> A selector to query page for
• pageFunction <function> Function to be evaluated in browser context
• ...args <...Serializable|JSHandle> Arguments to pass to pageFunction
• returns: <Promise<Serializable>> Promise which resolves to the return value of pageFunction