如何填写一个输入字段使用木偶？

Just set value of input like this:

await page.$eval('#email', el => el.value = 'test@example.com');

Here is an example of using it on Wikipedia:

const puppeteer = require('puppeteer');


(async () => {
const browser = await puppeteer.launch();
const page = await browser.newPage();
await page.goto('https://en.wikipedia.org', {waitUntil: 'networkidle2'});


await page.waitForSelector('input[name=search]');


// await page.type('input[name=search]', 'Adenosine triphosphate');
await page.$eval('input[name=search]', el => el.value = 'Adenosine triphosphate');


await page.click('input[type="submit"]');
await page.waitForSelector('#mw-content-text');
const text = await page.evaluate(() => {
const anchor = document.querySelector('#mw-content-text');
return anchor.textContent;
});
console.log(text);
await browser.close();
})();

To extend the accepted answer above, you can use $eval with locally scoped variables too,

const myLocalValue = 'Adenosine triphosphate';
await page.$eval('input[name=search]', (el, value) => el.value = value, myLocalValue);

This will take 'myLocalValue' from the local scope, and pass it into the browser scope as 'value'

another way doing

await page.focus('#email')
await page.keyboard.type('test54')

page.evaluate()

You can use page.evaluate() to assign the email string to the value attribute of the element:

await page.evaluate(() => {
const email = document.querySelector('#email');
email.value = 'test@example.com';
});

For Puppeteer Sharp, the syntax is a little different, and there are 2 ways to do it, but one is better than the other. Here is a full example:

static async Task Main(string[] args)
{
await new BrowserFetcher().DownloadAsync(BrowserFetcher.DefaultChromiumRevision);


await using (var browser = await Puppeteer.LaunchAsync(new LaunchOptions { Headless = true, Product = Product.Chrome }))
await using (var page = await browser.NewPageAsync())
{
try
{
await page.GoToAsync(urlString);
await page.WaitForSelectorAsync("#btnSubmit");


await ReplaceText(page, "#inputUsernameId", usernameString);
await ReplaceText(page, "#inputPasswordId", passwordString);


await page.ClickAsync("#btnSubmit");
await page.WaitForNavigationAsync();  // Optional, if the page is changing
}
catch (Exception ex)
{
Console.WriteLine(ex);
// Handle me / Log me
throw;
}
}
}


private static async Task ReplaceText(Page page, string selector, string replacementValue)
{
await page.WaitForSelectorAsync(selector).ConfigureAwait(false);
await page.EvaluateExpressionAsync($"document.querySelector(\"{selector}\").value = \"{replacementValue}\"").ConfigureAwait(false);


// Alternative older method below (not as reliable with async, but works):
// await ele.FocusAsync().ConfigureAwait(false);
//
// await page.Keyboard.DownAsync("Control").ConfigureAwait(false);
// await ele.PressAsync("A").ConfigureAwait(false);
// await page.Keyboard.UpAsync("Control").ConfigureAwait(false);
// await ele.PressAsync("Backspace").ConfigureAwait(false);
//
// await ele.TypeAsync(replacementText).ConfigureAwait(false);
// await ele.PressAsync("Tab").ConfigureAwait(false);
}

The selected answer didn't work for me in the latest version of Puppeteer(10.x). Instead what worked for me were the following commands.

test('should login', async () => {
const page = await browser.newPage();
page.setDefaultTimeout(6000);
await page.goto('https://www.saucedemo.com/');
await page.waitForSelector('#user-name');
await page.type('#user-name', 'standard_user');
await page.type('#password', 'secret_sauce');
await page.click('#login-button');
await page.waitForSelector('#contents_wrapper');});