whats puppeteerr in js code example

Example: puppeteer example nodejs

require('dotenv/config')
const puppeteer = require('puppeteer')

(async () => {
	try {
		const browser = await puppeteer.launch({
			headless: false,
			args: [
				'--allow-external-pages',
				'--allow-third-party-modules',
				'--data-reduction-proxy-http-proxies',
				'--no-sandbox'
			]
		})
		const context = await browser.createIncognitoBrowserContext()
		const page = await context.newPage()
		await page.goto('https://medium.com', { waitUntil: 'networkidle2' })
		await page.setUserAgent(process.env.USER_AGENT)
		// await page.setViewport({ width: 1920, height: 1080 })
		await page.evaluate(() => window.scrollBy(0, 1000))
		await page.waitForTimeout()
		await page.click('.qw a')
		await page.waitForNavigation({ waitUntil: 'networkidle2', delay: 1000 })
		await page.click('a[aria-label="Search"]')
		await page.waitForNavigation({ waitUntil: 'networkidle2', delay: 1000 })
		await page.focus('.js-searchInput')
		await page.type('.js-searchInput', 'react', { delay: 100 })
		await page.waitForSelector('.js-searchInput', { timeout: 1000 })
		await page.keyboard.press(String.fromCharCode(13))
		await page.waitForSelector('.js-postListHandle', { timeout: 1000 })
		await page.screenshot({ path: 'screnshoot.jpg', quality: 80 })

		await browser.close()
	} catch (err) {
		console.log(`'Puppeteer Error Detencted -> ${err}'`)
	}
})()