`))
defer ts.Close()
var nodes []*cdp.Node
if err := chromedp.Run(ctx,
chromedp.Navigate(ts.URL),
chromedp.Nodes("#section", &nodes, chromedp.ByQuery),
); err != nil {
log.Fatal(err)
}
sectionNode := nodes[0]
var queryRoot, queryFromNode, queryNestedSelector string
if err := chromedp.Run(ctx,
// Queries run from the document root by default, so Text will
// pick the first node it finds.
chromedp.Text(".content", &queryRoot, chromedp.ByQuery),
// We can specify a different node to run the query from; in
// this case, we can tailor the search within #section.
chromedp.Text(".content", &queryFromNode, chromedp.ByQuery, chromedp.FromNode(sectionNode)),
// A CSS selector like "#section > .content" achieves the same
// here, but FromNode allows us to use a node obtained by an
// entirely separate step, allowing for custom logic.
chromedp.Text("#section > .content", &queryNestedSelector, chromedp.ByQuery),
); err != nil {
log.Fatal(err)
}
fmt.Println("Simple query from the document root:", queryRoot)
fmt.Println("Simple query from the section node:", queryFromNode)
fmt.Println("Nested query from the document root:", queryNestedSelector)
// Output:
// Simple query from the document root: outer content
// Simple query from the section node: inner content
// Nested query from the document root: inner content
}
func Example_dump() {
ctx, cancel := chromedp.NewContext(context.Background())
defer cancel()
ts := httptest.NewServer(writeHTML(`
the content
`))
defer ts.Close()
const expr = `(function(d, id, v) {
var b = d.querySelector('body');
var el = d.createElement('div');
el.id = id;
el.innerText = v;
b.insertBefore(el, b.childNodes[0]);
})(document, %q, %q);`
s := fmt.Sprintf(expr, "thing", "a new thing!")
var buf bytes.Buffer
if err := chromedp.Run(ctx,
chromedp.Navigate(ts.URL),
chromedp.WaitVisible(`#content`),
chromedp.Evaluate(s, nil),
chromedp.WaitVisible(`#thing`),
chromedp.Dump(`document`, &buf, chromedp.ByJSPath),
); err != nil {
log.Fatal(err)
}
fmt.Println("Document tree:")
fmt.Print(buf.String())
// Output:
// Document tree:
// #document
// html
// html
// head
// body
// div#thing
// #text "a new thing!"
// div#content [style="display:block;"]
// #text "the content"
}
func Example_documentDump() {
ctx, cancel := chromedp.NewContext(context.Background())
defer cancel()
ts := httptest.NewServer(writeHTML(`
the content
`))
defer ts.Close()
const expr = `(function(d, id, v) {
var b = d.querySelector('body');
var el = d.createElement('div');
el.id = id;
el.innerText = v;
b.insertBefore(el, b.childNodes[0]);
})(document, %q, %q);`
s := fmt.Sprintf(expr, "thing", "a new thing!")
var nodes []*cdp.Node
if err := chromedp.Run(ctx,
chromedp.Navigate(ts.URL),
chromedp.Nodes(`document`, &nodes,
chromedp.ByJSPath, chromedp.Populate(-1, true)),
chromedp.WaitVisible(`#content`),
chromedp.Evaluate(s, nil),
chromedp.WaitVisible(`#thing`),
); err != nil {
log.Fatal(err)
}
fmt.Println("Document tree:")
fmt.Print(nodes[0].Dump(" ", " ", false))
// Output:
// Document tree:
// #document
// html
// html
// head
// body
// div#thing
// #text "a new thing!"
// div#content [style="display:block;"]
// #text "the content"
}
func ExampleFullScreenshot() {
ctx, cancel := chromedp.NewContext(context.Background())
defer cancel()
var buf []byte
if err := chromedp.Run(ctx,
chromedp.Navigate(`https://google.com`),
chromedp.FullScreenshot(&buf, 90),
); err != nil {
log.Fatal(err)
}
if err := os.WriteFile("fullScreenshot.jpeg", buf, 0o644); err != nil {
log.Fatal(err)
}
fmt.Println("wrote fullScreenshot.jpeg")
// Output:
// wrote fullScreenshot.jpeg
}
func ExampleEvaluate() {
ctx, cancel := chromedp.NewContext(context.Background())
defer cancel()
// Ignore the result:
{
if err := chromedp.Run(ctx,
chromedp.Evaluate(`window.scrollTo(0, 100)`, nil),
); err != nil {
log.Fatal(err)
}
}
// Receive a primary value:
{
var sum int
if err := chromedp.Run(ctx,
chromedp.Evaluate(`1+2`, &sum),
); err != nil {
log.Fatal(err)
}
fmt.Println(sum)
}
// ErrJSUndefined:
{
var val int
if err := chromedp.Run(ctx,
chromedp.Evaluate(`undefined`, &val),
); err != nil {
fmt.Println(err)
}
}
// ErrJSNull:
{
var val int
if err := chromedp.Run(ctx,
chromedp.Evaluate(`null`, &val),
); err != nil {
fmt.Println(err)
}
}
// Accept undefined/null result:
{
var val *int
if err := chromedp.Run(ctx,
chromedp.Evaluate(`undefined`, &val),
); err != nil {
log.Fatal(err)
}
fmt.Println(val)
}
// Receive an array value:
{
var val []int
if err := chromedp.Run(ctx,
chromedp.Evaluate(`[1,2]`, &val),
); err != nil {
log.Fatal(err)
}
fmt.Println(val)
}
// Map and Slice accept undefined/null:
{
var val []int
if err := chromedp.Run(ctx,
chromedp.Evaluate(`null`, &val),
); err != nil {
log.Fatal(err)
}
fmt.Println("slice is nil:", val == nil)
}
// Receive the raw bytes:
{
var buf []byte
if err := chromedp.Run(ctx,
chromedp.Evaluate(`alert`, &buf),
); err != nil {
log.Fatal(err)
}
fmt.Printf("%s\n", buf)
}
// Receive the RemoteObject:
{
var res *runtime.RemoteObject
if err := chromedp.Run(ctx,
chromedp.Evaluate(`alert`, &res),
); err != nil {
log.Fatal(err)
}
if res.ObjectID != "" {
fmt.Println("objectId is present")
}
}
// Output:
// 3
// encountered an undefined value
//
// [1 2]
// slice is nil: true
// {}
// objectId is present
}