3.3 KiB
About chromedp 
Package chromedp is a faster, simpler way to drive browsers in Go using the Chrome Debugging Protocol (for Chrome, Edge, Safari, etc) without external dependencies (ie, Selenium, PhantomJS, etc).
NOTE: chromedp's API is currently unstable, and may change at a moments notice. There are likely extremely bad bugs lurking in this code. CAVEAT USER.
Installation
Install in the usual way:
go get -u github.com/knq/chromedp
Usage
Below is a simple Google search performed using chromedp (taken from examples/simple):
This example shows logic for a simple search for a known website, clicking on the right link, and then taking a screenshot of a specific element on the loaded page and saving that to a local file on disk.
// examples/simple/main.go
package main
import (
"context"
"fmt"
"io/ioutil"
"log"
"time"
cdp "github.com/knq/chromedp"
cdptypes "github.com/knq/chromedp/cdp"
)
func main() {
var err error
// create context
ctxt, cancel := context.WithCancel(context.Background())
defer cancel()
// create chrome instance
c, err := cdp.New(ctxt, cdp.WithLog(log.Printf))
if err != nil {
log.Fatal(err)
}
// run task list
var site, res string
err = c.Run(ctxt, googleSearch("site:brank.as", "Home", &site, &res))
if err != nil {
log.Fatal(err)
}
// shutdown chrome
err = c.Shutdown(ctxt)
if err != nil {
log.Fatal(err)
}
// wait for chrome to finish
err = c.Wait()
if err != nil {
log.Fatal(err)
}
log.Printf("saved screenshot from search result listing `%s` (%s)", res, site)
}
func googleSearch(q, text string, site, res *string) cdp.Tasks {
var buf []byte
sel := fmt.Sprintf(`//a[text()[contains(., '%s')]]`, text)
return cdp.Tasks{
cdp.Navigate(`https://www.google.com`),
cdp.WaitVisible(`#hplogo`, cdp.ByID),
cdp.SendKeys(`#lst-ib`, q+"\n", cdp.ByID),
cdp.WaitVisible(`#res`, cdp.ByID),
cdp.Text(sel, res),
cdp.Click(sel),
cdp.WaitVisible(`a[href="/brankas-for-business"]`, cdp.ByQuery),
cdp.WaitNotVisible(`.preloader-content`, cdp.ByQuery),
cdp.Location(site),
cdp.ScrollIntoView(`.banner-section.third-section`, cdp.ByQuery),
cdp.Sleep(2 * time.Second), // wait for animation to finish
cdp.Screenshot(`.banner-section.third-section`, &buf, cdp.ByQuery),
cdp.ActionFunc(func(context.Context, cdptypes.Handler) error {
return ioutil.WriteFile("screenshot.png", buf, 0644)
}),
}
}
Please see the examples directory for some more examples, and please refer to the GoDoc API listing for a summary of the API and Actions.
Links + Resources
TODO
- Move timeouts to context (defaults)
- Implement more query selector options (allow over riding context timeouts)
- Contextual actions for "dry run" (or via an accumulator?)
- Network loader / manager
- Profiler