Overview

Rod is a High-level Chrome Devtools controller directly based on Chrome DevTools Protocol. Rod also tries to expose low-level interfaces to users, so that whenever a function is missing users can easily send control requests to the browser directly.

Features

• Fluent interface design to reduce verbose code
• Chained context design, intuitive to timeout or cancel the long-running task
• Debugging friendly, auto input tracing, remote monitoring headless browser
• Automatically find or download chrome
• No external dependencies, CI tested on Linux, Mac, and Windows
• High-level helpers like WaitStable, WaitRequestIdle, GetDownloadFile, Resource
• Two-step WaitEvent design, never miss an event
• Correctly handles nested iframes
• No zombie chrome process after the crash (how it works)

Examples

Here are the basic examples. For more details, please read the unit tests.

A cli translator example.

How it works

Here's the common start process of Rod:

1. Try to connect to a Chrome Devtools endpoint, if not found try to launch a local browser, if still not found try to download one, then connect again. The lib to handle it is here.

2. Use the JSON-RPC protocol to talk to the browser endpoint to control it. The lib to handle it is here.

3. To control a specific page, Rod will first inject a js helper script to it. Rod uses it to query and manipulate the page content. The js lib is here.

FAQ

How to use Rod inside a docker container

To let rod work with docker is very easy. Here's the example to run the unit tests of Rod with docker:

# cd to the root dir of rod repo
docker run -v $(pwd):/t -w /t ysmood/rod:go

How to contribute for Rod

Your help is more than welcome! Even just open an issue to ask a question may greatly help others.

You might want to learn the basics of Go Testing, Sub-tests, and Test Suite first.

You can get started by reading the unit tests by their nature hierarchy: Browser -> Page -> Element. So you read order will be something like browser_test.go -> page_test.go -> element_test.go. The test is intentionally being designed to be easily understandable.

Here an example to run a single test case: go test -v -run Test/TestClick, TestClick is the function name you want to run.

We trade off code lines to reduce function call distance to the source code of Golang itself. You may see redundant code everywhere to reduce the use of interfaces or dynamic tricks. So that everything should map to your brain like a tree, not a graph. So that you can always jump from one definition to another in a uni-directional manner, the reverse search should be rare.

Why another puppeteer like lib

There are a lot of great projects, but no one is perfect, choose the best one that fits your needs is important.

• selenium

  It's slower by design because it encourages the use of hard-coded sleep. When work with Rod, you generally don't use sleep at all. Therefore it's more buggy to use selenium if the network is unstable. It's harder to setup and maintain because of extra dependencies like a browser driver.

• puppeteer

  With Puppeteer, you have to handle promise/async/await a lot. It requires a deep understanding of how promises works which are usually painful for QA to write automation tests. End to end tests usually requires a lot of sync operations to simulate human inputs, because Puppeteer is based on Nodejs all control signals it sends to chrome will be async calls, so it's unfriendly for QA from the beginning.

• chromedp

  With Chromedp, you have to use their verbose DSL like tasks to handle the main logic, because Chromedp uses several wrappers to handle execution with context and options which makes it very hard to understand their code when bugs happen. The DSL like wrapper also make the Go type useless when tracking issues.

  It's painful to use Chromedp to deal with iframes, this ticket is still open after years.

  When a crash happens, Chromedp will leave the zombie chrome process on Windows and Mac.

• cypress

  Cypress is very limited, for closed shadow dom or cross-domain iframes it's almost unusable. Read their limitation doc for more details.