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browserless

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browserless is an efficient way to interact with a headless browser built in top of puppeteer.

Highlights

Installation

You can install it via npm:

$ npm install browserless puppeteer --save

browserless is backed by puppeteer, so you need to install it as well.

You can use it next to puppeteer, puppeteer-core or puppeteer-firefox, interchangeably.

Usage

This is a full example for showcase all the browserless capabilities:

const createBrowser = require('browserless')
const termImg = require('term-img')

// First, create a browserless factory
// that it will keep a singleton process running
const browser = createBrowser()

// After that, you can create as many browser context
// as you need. The browser contexts won't share cookies/cache
// with other browser contexts.
const browserless = await browser.createContext()

// Perform the action you want, e.g., getting the HTML markup
const buffer = await browserless.screenshot('http://example.com', {
  device: 'iPhone 6'
})

console.log(termImg(buffer))

// After your task is done, destroy your browser context
await browserless.destroyContext()

// At the end, gracefully shutdown the browser process
await browser.close()

As you can see, browserless is implemented using a single browser process and creating/destroying specific browser contexts.

If you're already using puppeteer, you can upgrade to use browserless instead almost with no effort.

Additionally, you can use some specific packages in your codebase, interacting with them from puppeteer.

CLI

With the command-line interface (CLI) you can interact with browserless methods using a terminal, or through an automated system:

Just install @browserless/cli globally in your system using your favorite package manager:

npm install -g @browserless/cli

Initializing a browser

The browserless main method is for creating a headless browser.

const createBrowser = require('browserless')

const browser = createBrowser({
  timeout: 25000,
  lossyDeviceName: true,
  ignoreHTTPSErrors: true
})

Once the browser is initialized, some browser high level methods are available:

// Now, just call `createContext` for creating a browser tab
const browserless = await browser.createContext({ retry: 2 })

const buffer = await browserless.screenshot('https://example.com')

// You call `destroyContext` to close the browser tab.
await browserless.destroyContext()

The browser keeps running until you explicitly close it:

// At the end, gracefully shutdown the browser process
await browser.close()

.constructor(options)

You can pass any puppeteer.launch#options.

Additionally, you can setup:

defaultDevice

type: string
default: 'Macbook Pro 13'

Sets a consistent device viewport for each page.

lossyDeviceName

type: boolean
default: false

It enables lossy detection over the device descriptor input.

const browserless = require('browserless')({ lossyDeviceName: true })

browserless.getDevice({ device: 'macbook pro 13' })
browserless.getDevice({ device: 'MACBOOK PRO 13' })
browserless.getDevice({ device: 'macbook pro' })
browserless.getDevice({ device: 'macboo pro' })

This setting is oriented for find the device even if the descriptor device name is not exactly the same.

mode

type: string
default: launch
values: 'launch' | 'connect'

It defines if browser should be spawned using puppeteer.launch or puppeteer.connect

timeout

type: number
default: 30000

This setting will change the default maximum navigation time.

puppeteer

type: Puppeteer
default: puppeteer|puppeteer-core|puppeteer-firefox

It's automatically detected based on your dependencies being supported puppeteer, puppeteer-core or puppeteer-firefox.

.createContext(options)

After initialize the browser, you can create browser context that is equivalente to open a tab:

const browserless = browser.createContext({
  retry: 2
})

Every browser context is isolated. They won't share cookies/cache with other browser contexts. They also can contain specific options.

options

Any browser.createIncognitoBrowserContext#options can be passed.

Additionally, you can setup:

retry

type: number
default: 2

The number of retries that can be performed before considering a navigation as failed.

.browser()

It returns the internal Browser instance.

const headlessBrowser = await browser.browser()

console.log('My headless browser PID is', headlessBrowser.process().pid)

.respawn()

It will respawn the internal browser.

const getPID = promise => (await promise).process().pid

console.log('Process PID:', await getPID(browser.browser()))

await browser.respawn()

console.log('Process PID:', await getPID(browser.browser()))

This method is an implementation detail, normally you don't need to call it.

.close()

It will close the internal browser.

const exitHook = require('exit-hook')

// automatically teardown resources after
// `process.exit` is called
exitHook(browser.close())

Using a browser

.html(url, options)

It serializes the content from the target url into HTML.

const html = await browserless.html('https://example.com')

console.log(html)
// => "<!DOCTYPE html><html><head>…"

options

See browserless.goto to know all the options and values supported.

.text(url, options)

It serializes the content from the target url into plain text.

const text = await browserless.text('https://example.com')

console.log(text) 
// => "Example Domain\nThis domain is for use in illustrative…"

options

See browserless.goto to know all the options and values supported.

.pdf(url, options)

It generates the PDF version of a website behind an url.

const buffer = await browserless.pdf('https://example.com')

console.log(`PDF generated in ${buffer.byteLength()} bytes`)

options

This method use the following options by default:

{
  margin: '0.35cm',
  printBackground: true,
  scale: 0.65
}

See browserless.goto to know all the options and values supported.

Also, any page.pdf option is supported.

Additionally, you can setup:

margin

type: stringstring[]
default: '0.35cm'

It sets paper margins. All possible units are:

  • px for pixel.
  • in for inches.
  • cm for centimeters.
  • mm for millimeters.

You can pass an object object specifying each corner side of the paper:

const buffer = await browserless.pdf(url.toString(), {
  margin: {
    top: '0.35cm',
    bottom: '0.35cm',
    left: '0.35cm',
    right: '0.35cm'
  }
})

Or, in case you pass an string, it will be used for all the sides:

const buffer = await browserless.pdf(url.toString(), {
  margin: '0.35cm'
})

.screenshot(url, options)

It takes a screenshot from the target url.

const buffer = await browserless.screenshot('https://example.com')

console.log(`Screenshot taken in ${buffer.byteLength()} bytes`)

options

This method use the following options by default:

{
  device: 'macbook pro 13'
}

See browserless.goto to know all the options and values supported.

Also, any page.screenshot option is supported.

Additionally, you can setup:

codeScheme

type: string
default: 'atom-dark'

When this value is present and the response 'Content-Type' header is 'json', it beautifies HTML markup using Prism.

The syntax highlight theme can be customized, being possible to setup:

  • A prism-themes identifier (e.g., 'dracula').
  • A remote URL (e.g., 'https://unpkg.com/prism-theme-night-owl').
element

type: string

Capture the DOM element matching the given CSS selector. It will wait for the element to appear in the page and to be visible.

overlay

type: object

After the screenshot has been taken, this option allows you to place the screenshot into a fancy overlay

You can configure the overlay specifying:

  • browser: It sets the browser image overlay to use, being light and dark supported values.
  • background: It sets the background to use, being supported to pass:
    • An hexadecimal/rgb/rgba color code, eg. #c1c1c1.
    • A CSS gradient, eg. linear-gradient(225deg, #FF057C 0%, #8D0B93 50%, #321575 100%)
    • An image url, eg. https://source.unsplash.com/random/1920x1080.
const buffer = await browserless.screenshot(url.toString(), {
  styles: [
    '.crisp-client, #cookies-policy { display: none; }'
  ],
  overlay: {
    browser: 'dark',
    background:
      'linear-gradient(45deg, rgba(255,18,223,1) 0%, rgba(69,59,128,1) 66%, rgba(69,59,128,1) 100%)'
  }
})

.destroyContext

It will destroy the current browser context.

const browserless = await browser.createContext({ retry: 0 })

const content = await browserless.html('https://example.com')

await browserless.destroyContext()

.getDevice(options)

Giving a specific device descriptons, this method will be the devices settings for it.

browserless.getDevice({ device: 'Macbook Pro 15' })

// => {
//   userAgent: 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/62.0.3202.89 Safari/537.36',
//   viewport: {
//     width: 1440,
//     height: 900,
//     deviceScaleFactor: 2,
//     isMobile: false,
//     hasTouch: false,
//     isLandscape: false
//   }
// }

It extends from puppeteer.devices, adding some missing devices there.

options

device

type: string

The device descriptor name. It's used to find the rest presets associated with it.

When lossyDeviceName is enabled, a fuzzy search rather than a strict search will be performed in order to maximize getting a result back.

viewport

type: object

An extra of viewport settings that will be merged with the device presets.

browserless.getDevice({
  device: 'iPad',
  viewport: {
    isLandscape: true
  }
})
headers

type: object

An extra of headers that will be merged with the device presets.

browserless.getDevice({
  device: 'iPad',
  headers: {
    'user-agent': 'googlebot'
  }
})

.evaluate(fn, gotoOpts)

It exposes an interface for creating your own evaluate function, passing you the page and response.

The fn will receive page and response as arguments:

const ping = browserless.evaluate((page, response) => ({
  statusCode: response.status(),
  url: response.url(),
  redirectUrls: response.request().redirectChain()
}))

await ping('https://example.com')
// {
//   "statusCode": 200,
//   "url": "https://example.com/",
//   "redirectUrls": []
// }

You don't need to close the page; It will be closed automatically.

Internally, the method performs a browserless.goto, being possible to pass extra arguments as second parameter:

const serialize = browserless.evaluate(
  page => page.evaluate(() => document.body.innerText),
  {
    waitUntil: 'domcontentloaded'
  }
)

await serialize('https://example.com')
// => '<!DOCTYPE html><html><div>…'

.goto(page, options)

It performs a page.goto with a lot of extra capabilities:

const page = await browserless.page()
const { response, device } = await browserless.goto(page, { url: 'http://example.com' })

options

Any option passed here will bypass to page.goto.

Additionally, you can setup:

abortTypes

type: array
default: []

It sets the ability to abort requests based on the resource type.

adblock

type: boolean
default: true

It enabled the builtin adblocker by Cliqz that aborts unnecessary third party requests associated with ads services.

animations

type: boolean
default: false

Disable CSS animations and transitions, also it sets prefers-reduced-motion consequently.

click

type: stringstring[]

Click the DOM element matching the given CSS selector.

colorScheme

type: string
default: 'no-preference'

Sets prefers-color-scheme CSS media feature, used to detect if the user has requested the system use a 'light' or 'dark' color theme.

device

type: string
default: 'macbook pro 13'

It specifies the device descriptor to use in order to retrieve userAgent and viewport.

evasions

type: string[]
default: require('@browserless/goto').evasions

It makes your Headless undetectable, preventing to being blocked.

These techniques are used by antibot systems to check if you are a real browser and block any kind of automated access. All the evasion techniques implemented are:

Evasion Description
chromeRuntime Ensure window.chrome is defined.
stackTraces Prevent detect Puppeteer via variable name.
mediaCodecs Ensure media codedcs are defined.
navigatorPermissions Mock over Notification.permissions.
navigatorPlugins Ensure your browser has NavigatorPlugins defined.
navigatorWebdriver Ensure Navigator.webdriver exists.
randomizeUserAgent Use a different User-Agent every time.
webglVendor Ensure WebGLRenderingContext & WebGL2RenderingContext are defined.

The evasion techniques are enabled by default. You can omit techniques just filtering them:

const createBrowser = require('browserless')

const evasions = require('@browserless/goto').evasions.filter(
  evasion => evasion !== 'randomizeUserAgent'
)

const browser = createBrowser({ evasions })
headers

type: object

An object containing additional HTTP headers to be sent with every request.

const browserless = require('browserless')

const page = await browserless.page()
await browserless.goto(page, {
  url: 'http://example.com',
  headers: {
    'user-agent': 'googlebot',
    cookie: 'foo=bar; hello=world'
  }
})

This sets visibility: hidden on the matched elements.

html

type: string

In case you provide HTML markup, a page.setContent avoiding fetch the content from the target URL.

javascript

type: boolean
default: true

When it's false, it disables JavaScript on the current page.

mediaType

type: string
default: 'screen'

Changes the CSS media type of the page using page.emulateMediaType.

modules

type: stringstring[]

Injects <script type="module"> into the browser page.

It can accept:

  • Absolute URLs (e.g., 'https://cdn.jsdelivr.net/npm/@microlink/mql@0.3.12/src/browser.js').
  • Local file (e.g., `'local-file.js').
  • Inline code (e.g., "document.body.style.backgroundColor = 'red'").
const buffer = await browserless.screenshot(url.toString(), {
  modules: [
    'https://cdn.jsdelivr.net/npm/@microlink/mql@0.3.12/src/browser.js',
    'local-file.js',
    "document.body.style.backgroundColor = 'red'"
  ]
})
onPageRequest

type:function

Associate a handler for every request in the page.

scripts

type: stringstring[]

Injects <script> into the browser page.

It can accept:

  • Absolute URLs (e.g., 'https://cdn.jsdelivr.net/npm/@microlink/mql@0.3.12/src/browser.js').
  • Local file (e.g., `'local-file.js').
  • Inline code (e.g., "document.body.style.backgroundColor = 'red'").
const buffer = await browserless.screenshot(url.toString(), {
  scripts: [
    'https://cdn.jsdelivr.net/npm/jquery@3.4.1/dist/jquery.min.js',
    'local-file.js',
    "document.body.style.backgroundColor = 'red'"
  ]
})

Prefer to use modules whenever possible.

scroll

type: string

Scroll to the DOM element matching the given CSS selector.

styles

type: stringstring[]

Injects <style> into the browser page.

It can accept:

  • Absolute URLs (e.g., 'https://cdn.jsdelivr.net/npm/hack@0.8.1/dist/dark.css').
  • Local file (e.g., `'local-file.css').
  • Inline code (e.g., "body { background: red; }").
const buffer = await browserless.screenshot(url.toString(), {
  styles: [
    'https://cdn.jsdelivr.net/npm/hack@0.8.1/dist/dark.css',
    'local-file.css',
    'body { background: red; }'
  ]
})
timezone

type: string

It changes the timezone of the page.

url

type: string

The target URL.

viewport

It will setup a custom viewport, using page.setViewport method.

waitForSelector

type:string

Wait a quantity of time, selector or function using page.waitForSelector.

waitForTimeout

type:number

Wait a quantity of time, selector or function using page.waitForTimeout.

waitUntil

type: string | string[]
default: 'auto'
values: 'auto' | 'load' | 'domcontentloaded' | 'networkidle0' | 'networkidle2'

When to consider navigation succeeded.

If you provide an array of event strings, navigation is considered to be successful after all events have been fired.

Events can be either:

  • 'auto': A combination of 'load' and 'networkidle2' in a smart way to wait the minimum time necessary.
  • 'load': Consider navigation to be finished when the load event is fired.
  • 'domcontentloaded': Consider navigation to be finished when the DOMContentLoaded event is fired.
  • 'networkidle0': Consider navigation to be finished when there are no more than 0 network connections for at least 500 ms.
  • 'networkidle2': Consider navigation to be finished when there are no more than 2 network connections for at least 500 ms.

.context()

It returns the BrowserContext associated with your instance.

const browserContext = await browserless.context()

console.log({ isIncognito: browserContext.isIncognito() })
// => { isIncognito: true }

.page()

It returns a standalone Page associated with the current browser context.

const page = await browserless.page()
await page.content()
// => '<html><head></head><body></body></html>'

Executing arbitrary code

The @browserless/function package provides an isolated vm scope to run arbitrary JavaScript code with runtime access to a browser page:

const createFunction = require('@browserless/function')

const code = async ({ page }) => page.evaluate('jQuery.fn.jquery')

const version = createFunction(code)

const { isFulfilled, isRejected, value } = await version('https://jquery.com')

// => {
//   isFulfilled: true,
//   isRejected: false,
//   value: '1.13.1'
// }

options

Besides the following properties, any other argument provided will be available during the code execution.

vmOpts

The hosted code is also running inside a secure sandbox created via vm2.

gotoOpts

Any goto#options can be passed for tuning the internal URL resolution.

Runing Lighthouse

The @browserless/lighthouse package provides you the setup for running Lighthouse reports backed by browserless.

const lighthouse = require('@browserless/lighthouse')
const { writeFile } = require('fs/promises')

const report = await lighthouse('https://example.com')

await writeFile('report.json', JSON.stringify(report, null, 2))

The report will be generated url, extending from lighthouse:default settings, being these settings the same than Google Chrome Audits reports on Developer Tools.

options

The second argument can contain lighthouse specific settings The following options are used by default:

{
  logLevel: 'error',
  output: 'json',
  device: 'desktop',
  onlyCategories: ['perfomance', 'best-practices', 'accessibility', 'seo']
}

See Lighthouse configuration to know all the options and values supported.

Additionally, you can setup:

The lighthouse execution runs as a worker thread, any worker#options are supported.

getBrowserless

type: function
default: require('browserless')

The browserless instance to use for getting the browser.

logLevel

type: string
default: 'error'
values: 'silent' | 'error' | 'info' | 'verbose'

The level of logging to enable.

output

type: string | string[]
default: 'json'
values: 'json' | 'csv' | 'html'

The type(s) of report output to be produced.

device

type: string
default: 'desktop'
values: 'desktop' | 'mobile' | 'none'

How emulation (useragent, device screen metrics, touch) should be applied. 'none' indicates Lighthouse should leave the host browser as-is.

onlyCategories

type: string[]null
default: ['performance', 'best-practices', 'accessibility', 'seo']
values: 'performance' | 'best-practices' | 'accessibility' | 'pwa' | 'seo'

Includes only the specified categories in the final report.

Packages

browserless is internally divided into multiple packages for ensuring just use the minimum quantity of code necessary for your use case.

Package Version
browserless npm
@browserless/benchmark npm
@browserless/cli npm
@browserless/devices npm
@browserless/examples npm
@browserless/errors npm
@browserless/function npm
@browserless/goto npm
@browserless/pdf npm
@browserless/screenshot npm
@browserless/lighthouse npm

FAQ

Q: Why use browserless over puppeteer?

browserless not replace puppeteer, it complements. It's just a syntactic sugar layer over official Headless Chrome oriented for production scenarios.

Q: Why do you block ads scripts by default?

Headless navigation is expensive compared with just fetch the content from a website.

In order to speed up the process, we block ads scripts by default because they are so bloat.

Q: My output is different from the expected

Probably browserless was too smart and it blocked a request that you need.

You can active debug mode using DEBUG=browserless environment variable in order to see what is happening behind the code:

Consider open an issue with the debug trace.

Q: I want to use browserless with my AWS Lambda like project

Yes, check chrome-aws-lambda to setup AWS Lambda with a binary compatible.

License

browserless © Microlink, released under the MIT License.
Authored and maintained by Microlink with help from contributors.

The logo has been designed by xinh studio.

microlink.io · GitHub microlinkhq · Twitter @microlinkhq