110 lines
2.8 KiB
Markdown
110 lines
2.8 KiB
Markdown
# About chromedp
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Package chromedp is a faster, simpler way to drive browsers in Go using the
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[Chrome Debugging Protocol](https://developer.chrome.com/devtools/docs/debugger-protocol)
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(for Chrome, Edge, Safari, etc) without external dependencies (ie, Selenium, PhantomJS, etc).
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**NOTE:** chromedp's API is currently unstable, and may change at a moments
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notice. There are likely extremely bad bugs lurking in this code. **CAVEAT USER**.
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## Installation
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Install in the usual way:
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```sh
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go get -u github.com/knq/chromedp
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```
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## Usage
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Below is a simple Google search performed using chromedp (taken from
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[examples/simple](examples/simple/main.go)):
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This example shows logic for a simple search for a known website, clicking on
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the right link, and then taking a screenshot of a specific element on the
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loaded page and saving that to a local file on disk.
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```go
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package main
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import (
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"context"
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"fmt"
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"io/ioutil"
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"log"
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"time"
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cdp "github.com/knq/chromedp"
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cdptypes "github.com/knq/chromedp/cdp"
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)
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func main() {
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var err error
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// create context
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ctxt, cancel := context.WithCancel(context.Background())
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defer cancel()
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// create chrome instance
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c, err := cdp.New(ctxt)
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if err != nil {
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log.Fatal(err)
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}
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// run task list
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var site, res string
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err = c.Run(ctxt, googleSearch("site:brank.as", "Easy Money Management", &site, &res))
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if err != nil {
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log.Fatal(err)
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}
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// shutdown chrome
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err = c.Shutdown(ctxt)
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if err != nil {
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log.Fatal(err)
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}
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// wait for chrome to finish
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err = c.Wait()
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if err != nil {
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log.Fatal(err)
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}
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log.Printf("saved screenshot of #testimonials from search result listing `%s` (%s)", res, site)
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}
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func googleSearch(q, text string, site, res *string) cdp.Tasks {
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var buf []byte
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sel := fmt.Sprintf(`//a[text()[contains(., '%s')]]`, text)
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return cdp.Tasks{
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cdp.Navigate(`https://www.google.com`),
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cdp.Sleep(2 * time.Second),
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cdp.WaitVisible(`#hplogo`, cdp.ByID),
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cdp.SendKeys(`#lst-ib`, q, cdp.ByID),
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cdp.Click(`input[name="btnK"]`, cdp.ByQuery),
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cdp.WaitNotVisible(`input[name="btnI"]`, cdp.ByQuery),
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cdp.Text(sel, res),
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cdp.Click(sel),
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cdp.Sleep(2 * time.Second),
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cdp.WaitVisible(`#footer`, cdp.ByQuery),
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cdp.WaitNotVisible(`div.v-middle > div.la-ball-clip-rotate`, cdp.ByQuery),
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cdp.Location(site),
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cdp.Screenshot(`#testimonials`, &buf, cdp.ByID),
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cdp.ActionFunc(func(context.Context, cdptypes.FrameHandler) error {
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return ioutil.WriteFile("testimonials.png", buf, 0644)
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}),
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}
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}
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```
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Please see the [examples](examples/) directory for examples.
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## TODO
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* Move timeouts to context (defaults)
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* Implement more query selector options (allow over riding context timeouts)
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* Contextual actions for "dry run" (or via an accumulator?)
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* Network loader / manager
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* More examples
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* Profiler
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* Unit tests / coverage: travis-ci + coveralls integration
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