Updating README.md

README.md

@@ -17,6 +17,86 @@ go get -u github.com/knq/chromedp
 
 ## Usage
 
+Below is a simple Google search performed using chromedp (taken from
+[examples/simple](examples/simple/main.go)):
+
+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.
+
+```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)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	// run task list
+	var site, res string
+	err = c.Run(ctxt, googleSearch("site:brank.as", "Easy Money Management", &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 of #testimonials 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.Sleep(2 * time.Second),
+		cdp.WaitVisible(`#hplogo`, cdp.ByID),
+		cdp.SendKeys(`#lst-ib`, q, cdp.ByID),
+		cdp.Click(`input[name="btnK"]`, cdp.ByQuery),
+		cdp.WaitNotVisible(`input[name="btnI"]`, cdp.ByQuery),
+		cdp.Text(sel, res),
+		cdp.Click(sel),
+		cdp.Sleep(2 * time.Second),
+		cdp.WaitVisible(`#footer`, cdp.ByQuery),
+		cdp.WaitNotVisible(`div.v-middle > div.la-ball-clip-rotate`, cdp.ByQuery),
+		cdp.Location(site),
+		cdp.Screenshot(`#testimonials`, &buf, cdp.ByID),
+		cdp.ActionFunc(func(context.Context, cdptypes.FrameHandler) error {
+			return ioutil.WriteFile("testimonials.png", buf, 0644)
+		}),
+	}
+}
+```
+
 Please see the [examples](examples/) directory for examples.
 
 ## TODO