Added possibility to dispatch events on node

Gopkg.lock

@@ -66,7 +66,7 @@
   version = "v4.2.1"
 
 [[projects]]
-  digest = "1:383ac09778833e583aa5f74cf52a71367c72ba43a7de1460e8ff95182ad93b3b"
+  digest = "1:7ffdd69928c5153fc351132aa80bbcc18a8f8122de1ba592cf42dccb65732361"
   name = "github.com/mafredri/cdp"
   packages = [
     ".",
@@ -115,6 +115,7 @@
     "protocol/tethering",
     "protocol/tracing",
     "rpcc",
+    "session",
   ]
   pruneopts = "UT"
   revision = "75b0ecc5efcff27ac756a33ec71f0db75dc3d21c"
@@ -180,25 +181,6 @@
   pruneopts = "UT"
   revision = "1d60e4601c6fd243af51cc01ddf169918a5407ca"
 
-[[projects]]
-  digest = "1:45ed1634373de798161249f031804bac6f5ec7707bbae94047ecd8e69875936c"
-  name = "golang.org/x/text"
-  packages = [
-    "internal/colltab",
-    "internal/gen",
-    "internal/tag",
-    "internal/triegen",
-    "internal/ucd",
-    "language",
-    "search",
-    "transform",
-    "unicode/cldr",
-    "unicode/norm",
-  ]
-  pruneopts = "UT"
-  revision = "f21a4dfb5e38f5895301dc265a8def02365cc3d0"
-  version = "v0.3.0"
-
 [solve-meta]
   analyzer-name = "dep"
   analyzer-version = 1
@@ -210,13 +192,17 @@
     "github.com/mafredri/cdp",
     "github.com/mafredri/cdp/devtool",
     "github.com/mafredri/cdp/protocol/dom",
+    "github.com/mafredri/cdp/protocol/emulation",
+    "github.com/mafredri/cdp/protocol/input",
+    "github.com/mafredri/cdp/protocol/page",
+    "github.com/mafredri/cdp/protocol/runtime",
     "github.com/mafredri/cdp/rpcc",
+    "github.com/mafredri/cdp/session",
     "github.com/pkg/errors",
     "github.com/sethgrid/pester",
     "github.com/smartystreets/goconvey/convey",
     "golang.org/x/net/html",
     "golang.org/x/sync/errgroup",
-    "golang.org/x/text/search",
   ]
   solver-name = "gps-cdcl"
   solver-version = 1

docs/examples/click.fql

@@ -0,0 +1,9 @@
+LET doc = DOCUMENT("https://github.com/", true)
+LET btn = ELEMENT(doc, ".HeaderMenu a")
+LET clicked = CLICK(btn)
+
+WAIT_ELEMENT(doc, '.IconNav', 5000)
+WAIT(5000)
+
+FOR el IN ELEMENTS(doc, '.IconNav a')
+    RETURN el.innerText

docs/examples/dynamic-page.fql

@@ -4,8 +4,6 @@ WAIT_ELEMENT(doc, '.chartTrack__details', 5000)
 
 LET tracks = ELEMENTS(doc, '.chartTrack__details')
 
-// LOG("found", LENGTH(tracks), "tracks")
-
 FOR track IN tracks
     LET username = ELEMENT(track, '.chartTrack__username')
     LET title = ELEMENT(track, '.chartTrack__title')

docs/examples/reddit.fql

@@ -1,8 +0,0 @@
-LET reddit = DOCUMENT("https://www.reddit.com/")
-LET urls = ELEMENTS(reddit, 'a[data-click-id="body"]')
-
-FOR url IN urls
-    LET subreddit = DOCUMENT("https://www.reddit.com" + TRIM(url.attributes.href))
-    LET post = ELEMENT(subreddit, 'div[data-test-id="post-content"] > div:nth-child(2) > div')
-
-    RETURN { title: post.children[0].innerText }

pkg/stdlib/html/actions.go

@@ -0,0 +1,56 @@
+package html
+
+import (
+	"context"
+	"github.com/MontFerret/ferret/pkg/runtime/core"
+	"github.com/MontFerret/ferret/pkg/runtime/values"
+	"github.com/MontFerret/ferret/pkg/stdlib/html/driver/browser"
+)
+
+/*
+ *
+ */
+func Click(_ context.Context, args ...core.Value) (core.Value, error) {
+	err := core.ValidateArgs(args, 1, 2)
+
+	if err != nil {
+		return values.False, err
+	}
+
+	// CLICK(el)
+	if len(args) == 1 {
+		arg1 := args[0]
+
+		err := core.ValidateType(arg1, core.HtmlElementType)
+
+		if err != nil {
+			return values.False, err
+		}
+
+		el, ok := arg1.(*browser.HtmlElement)
+
+		if !ok {
+			return values.False, core.Error(core.ErrInvalidType, "expected dynamic element")
+		}
+
+		return el.Click()
+	} else {
+		// CLICK(doc, selector)
+		arg1 := args[0]
+		selector := args[1].String()
+
+		err = core.ValidateType(arg1, core.HtmlDocumentType)
+
+		if err != nil {
+			return values.None, err
+		}
+
+		doc, ok := arg1.(*browser.HtmlDocument)
+
+		if !ok {
+			return values.False, core.Error(core.ErrInvalidType, "expected dynamic document")
+		}
+
+		return doc.ClickBySelector(values.NewString(selector))
+	}
+}

pkg/stdlib/html/driver/browser/broker.go

@@ -0,0 +1,103 @@
+package browser
+
+import (
+	"context"
+	"fmt"
+	"github.com/MontFerret/ferret/pkg/runtime/core"
+	"github.com/mafredri/cdp/protocol/page"
+)
+
+type (
+	EventHandler func(event, message string)
+
+	EventBroker struct {
+		client   page.LifecycleEventClient
+		handlers map[string][]EventHandler
+		cancel   context.CancelFunc
+	}
+)
+
+func NewEventBroker(client page.LifecycleEventClient) *EventBroker {
+	return &EventBroker{
+		client,
+		make(map[string][]EventHandler),
+		nil,
+	}
+}
+
+func (broker *EventBroker) Start() error {
+	if broker.cancel != nil {
+		return core.Error(core.ErrInvalidOperation, "broker is already started")
+	}
+
+	ctx, cancel := context.WithCancel(context.Background())
+
+	broker.cancel = cancel
+
+	go func() {
+		for {
+			select {
+			case <-ctx.Done():
+				return
+			case <-broker.client.Ready():
+				reply, err := broker.client.Recv()
+
+				if err != nil {
+					fmt.Println("FAILED TO GET EVENT", err)
+					broker.Emit("error", err.Error())
+
+					return
+				}
+
+				fmt.Println("EVENT", reply.Name)
+
+				broker.Emit(reply.Name, "")
+			}
+		}
+	}()
+
+	return nil
+}
+
+func (broker *EventBroker) Stop() error {
+	if broker.cancel == nil {
+		return core.Error(core.ErrInvalidOperation, "broker is already stopped")
+	}
+
+	broker.cancel()
+	broker.client = nil
+
+	return nil
+}
+
+func (broker *EventBroker) Close() error {
+	if broker.cancel != nil {
+		broker.Stop()
+	}
+
+	return broker.client.Close()
+}
+
+func (broker *EventBroker) AddListener(event string, handler EventHandler) {
+	handlers, ok := broker.handlers[event]
+
+	if !ok {
+		handlers = make([]EventHandler, 0, 5)
+
+		broker.handlers[event] = handlers
+	}
+
+	handlers = append(handlers, handler)
+}
+
+func (broker *EventBroker) Emit(name, message string) {
+	handlers, ok := broker.handlers[name]
+
+	if !ok {
+		return
+	}
+
+	for _, handler := range handlers {
+		handler(name, message)
+	}
+}

pkg/stdlib/html/driver/browser/document.go

@@ -5,8 +5,11 @@ import (
 	"fmt"
 	"github.com/MontFerret/ferret/pkg/runtime/core"
 	"github.com/MontFerret/ferret/pkg/runtime/values"
+	"github.com/corpix/uarand"
 	"github.com/mafredri/cdp"
 	"github.com/mafredri/cdp/protocol/dom"
+	"github.com/mafredri/cdp/protocol/emulation"
+	"github.com/mafredri/cdp/protocol/page"
 	"github.com/mafredri/cdp/rpcc"
 	"strings"
 	"time"
@@ -16,6 +19,7 @@ type HtmlDocument struct {
 	*HtmlElement
 	conn   *rpcc.Conn
 	client *cdp.Client
+	events *EventBroker
 	url    string
 }
 
@@ -39,6 +43,13 @@ func NewHtmlDocument(
 			return client.Page.Enable(ctx)
 		},
 
+		func() error {
+			return client.Page.SetLifecycleEventsEnabled(
+				ctx,
+				page.NewSetLifecycleEventsEnabledArgs(true),
+			)
+		},
+
 		func() error {
 			return client.DOM.Enable(ctx)
 		},
@@ -46,44 +57,93 @@ func NewHtmlDocument(
 		func() error {
 			return client.Runtime.Enable(ctx)
 		},
+
+		func() error {
+			return client.Emulation.SetUserAgentOverride(
+				ctx,
+				emulation.NewSetUserAgentOverrideArgs(uarand.GetRandom()),
+			)
+		},
 	)
 
 	if err != nil {
 		return nil, err
 	}
 
-	loadEventFired, err := client.Page.LoadEventFired(ctx)
+	err = waitForLoadEvent(ctx, client)
 
 	if err != nil {
 		return nil, err
 	}
 
+	root, err := getRootElement(ctx, client)
+
+	if err != nil {
+		return nil, err
+	}
+
+	events, err := createEventBroker(ctx, client)
+
+	if err != nil {
+		return nil, err
+	}
+
+	doc := &HtmlDocument{
+		NewHtmlElement(client, root.NodeID, root),
+		conn,
+		client,
+		events,
+		url,
+	}
+
+	doc.init()
+
+	return doc, nil
+}
+
+func waitForLoadEvent(ctx context.Context, client *cdp.Client) error {
+	loadEventFired, err := client.Page.LoadEventFired(ctx)
+
+	if err != nil {
+		return err
+	}
+
 	_, err = loadEventFired.Recv()
 
 	if err != nil {
-		return nil, err
+		return err
 	}
 
-	loadEventFired.Close()
+	return loadEventFired.Close()
+}
 
+func getRootElement(ctx context.Context, client *cdp.Client) (dom.Node, error) {
 	args := dom.NewGetDocumentArgs()
 	args.Depth = PointerInt(-1) // lets load the entire document
 
 	d, err := client.DOM.GetDocument(ctx, args)
 
+	if err != nil {
+		return dom.Node{}, err
+	}
+
+	return d.Root, nil
+}
+
+func createEventBroker(ctx context.Context, client *cdp.Client) (*EventBroker, error) {
+	lfc, err := client.Page.LifecycleEvent(ctx)
+
 	if err != nil {
 		return nil, err
 	}
 
-	return &HtmlDocument{
-		&HtmlElement{client, d.Root.NodeID, d.Root, nil},
-		conn,
-		client,
-		url,
-	}, nil
+	return NewEventBroker(lfc), nil
 }
 
 func (doc *HtmlDocument) Close() error {
+	doc.events.Stop()
+	doc.events.Close()
+
 	doc.client.Page.Close(context.Background())
 
 	return doc.conn.Close()
@@ -112,6 +172,36 @@ func (doc *HtmlDocument) Compare(other core.Value) int {
 	}
 }
 
+func (doc *HtmlDocument) ClickBySelector(selector values.String) (values.Boolean, error) {
+	res, err := Eval(
+		doc.client,
+		fmt.Sprintf(`
+			var el = document.querySelector("%s");
+
+			if (el == null) {
+				return false;
+			}
+
+			var evt = new window.MouseEvent('click', { bubbles: true });
+			el.dispatchEvent(evt);
+
+			return true;
+		`, selector),
+		true,
+		false,
+	)
+
+	if err != nil {
+		return values.False, err
+	}
+
+	if res.Type() == core.BooleanType {
+		return res.(values.Boolean), nil
+	}
+
+	return values.False, nil
+}
+
 func (doc *HtmlDocument) WaitForSelector(selector values.String, timeout values.Int) error {
 	task := NewWaitTask(
 		doc.client,
@@ -125,9 +215,27 @@ func (doc *HtmlDocument) WaitForSelector(selector values.String, timeout values.
 			return null;
 		`, selector),
 		time.Millisecond*time.Duration(timeout),
+		DefaultPolling,
 	)
 
 	_, err := task.Run()
 
 	return err
 }
+
+func (doc *HtmlDocument) init() {
+	// doc.events.AddListener("")
+}
+
+func (doc *HtmlDocument) reload() error {
+	root, err := getRootElement(context.Background(), doc.client)
+
+	if err != nil {
+		return err
+	}
+
+	doc.url = *root.BaseURL
+	doc.id = root.NodeID
+
+	return nil
+}

pkg/stdlib/html/driver/browser/element.go

@@ -11,7 +11,6 @@ import (
 	"github.com/PuerkitoBio/goquery"
 	"github.com/mafredri/cdp"
 	"github.com/mafredri/cdp/protocol/dom"
-	"log"
 	"strconv"
 	"time"
 )
@@ -19,13 +18,17 @@ import (
 const DefaultTimeout = time.Second * 30
 
 type HtmlElement struct {
-	client     *cdp.Client
-	id         dom.NodeID
-	node       dom.Node
-	attributes *values.Object
+	client         *cdp.Client
+	id             dom.NodeID
+	nodeType       values.Int
+	nodeName       values.String
+	value          string
+	attributes     *values.Object
+	children       []dom.NodeID
+	loadedChildren *values.Array
 }
 
-func NewHtmlElement(
+func LoadElement(
 	client *cdp.Client,
 	id dom.NodeID,
 ) (*HtmlElement, error) {
@@ -42,15 +45,46 @@ func NewHtmlElement(
 		dom.
 			NewDescribeNodeArgs().
 			SetNodeID(id).
-			SetDepth(-1),
+			SetDepth(1),
 	)
 
 	if err != nil {
-		log.Println("ERROR:", err)
 		return nil, core.Error(err, strconv.Itoa(int(id)))
 	}
 
-	return &HtmlElement{client, id, node.Node, nil}, nil
+	return NewHtmlElement(client, id, node.Node), nil
+}
+
+func NewHtmlElement(
+	client *cdp.Client,
+	id dom.NodeID,
+	node dom.Node,
+) *HtmlElement {
+	el := new(HtmlElement)
+	el.client = client
+	el.id = id
+	el.nodeType = values.NewInt(node.NodeType)
+	el.nodeName = values.NewString(node.NodeName)
+	el.value = ""
+	el.attributes = parseAttrs(node.Attributes)
+
+	var childCount int
+
+	if node.ChildNodeCount != nil {
+		childCount = *node.ChildNodeCount
+	}
+
+	if node.Value != nil {
+		el.value = *node.Value
+	}
+
+	el.children = make([]dom.NodeID, childCount)
+
+	for idx, child := range node.Children {
+		el.children[idx] = child.NodeID
+	}
+
+	return el
 }
 
 func (el *HtmlElement) Close() error {
@@ -69,19 +103,19 @@ func (el *HtmlElement) MarshalJSON() ([]byte, error) {
 	defer cancelFn()
 
 	args := dom.NewGetOuterHTMLArgs()
-	args.NodeID = &el.node.NodeID
+	args.NodeID = &el.id
 
 	reply, err := el.client.DOM.GetOuterHTML(ctx, args)
 
 	if err != nil {
-		return nil, core.Error(err, strconv.Itoa(int(el.node.NodeID)))
+		return nil, core.Error(err, strconv.Itoa(int(el.id)))
 	}
 
 	return json.Marshal(reply.OuterHTML)
 }
 
 func (el *HtmlElement) String() string {
-	return *el.node.Value
+	return el.value
 }
 
 func (el *HtmlElement) Compare(other core.Value) int {
@@ -89,8 +123,8 @@ func (el *HtmlElement) Compare(other core.Value) int {
 	case core.HtmlDocumentType:
 		other := other.(*HtmlElement)
 
-		id := int(el.node.NodeID)
-		otherId := int(other.node.NodeID)
+		id := int(el.id)
+		otherId := int(other.id)
 
 		if id == otherId {
 			return 0
@@ -111,13 +145,13 @@ func (el *HtmlElement) Compare(other core.Value) int {
 }
 
 func (el *HtmlElement) Unwrap() interface{} {
-	return el.node
+	return el
 }
 
 func (el *HtmlElement) Hash() int {
 	h := sha512.New()
 
-	out, err := h.Write([]byte(*el.node.Value))
+	out, err := h.Write([]byte(el.value))
 
 	if err != nil {
 		return 0
@@ -131,34 +165,22 @@ func (el *HtmlElement) Value() core.Value {
 }
 
 func (el *HtmlElement) Length() values.Int {
-	if el.node.ChildNodeCount == nil {
-		return values.ZeroInt
-	}
-
-	return values.NewInt(*el.node.ChildNodeCount)
+	return values.NewInt(len(el.children))
 }
 
 func (el *HtmlElement) NodeType() values.Int {
-	return values.NewInt(el.node.NodeType)
+	return el.nodeType
 }
 
 func (el *HtmlElement) NodeName() values.String {
-	return values.NewString(el.node.NodeName)
+	return el.nodeName
 }
 
 func (el *HtmlElement) GetAttributes() core.Value {
-	if el.attributes == nil {
-		el.attributes = el.parseAttrs()
-	}
-
 	return el.attributes
 }
 
 func (el *HtmlElement) GetAttribute(name values.String) core.Value {
-	if el.attributes == nil {
-		el.attributes = el.parseAttrs()
-	}
-
 	val, found := el.attributes.Get(name)
 
 	if !found {
@@ -169,27 +191,19 @@ func (el *HtmlElement) GetAttribute(name values.String) core.Value {
 }
 
 func (el *HtmlElement) GetChildNodes() core.Value {
-	arr := values.NewArray(len(el.node.Children))
-
-	for idx := range el.node.Children {
-		el := el.GetChildNode(values.NewInt(idx))
-
-		if el != values.None {
-			arr.Push(el)
-		}
+	if el.loadedChildren == nil {
+		el.loadedChildren = loadNodes(el.client, el.children)
 	}
 
-	return arr
+	return el.loadedChildren
 }
 
 func (el *HtmlElement) GetChildNode(idx values.Int) core.Value {
-	if el.Length() < idx {
-		return values.None
+	if el.loadedChildren == nil {
+		el.loadedChildren = loadNodes(el.client, el.children)
 	}
 
-	childNode := el.node.Children[idx]
-
-	return &HtmlElement{el.client, childNode.NodeID, childNode, nil}
+	return el.loadedChildren.Get(idx)
 }
 
 func (el *HtmlElement) QuerySelector(selector values.String) core.Value {
@@ -199,11 +213,10 @@ func (el *HtmlElement) QuerySelector(selector values.String) core.Value {
 	found, err := el.client.DOM.QuerySelector(ctx, selectorArgs)
 
 	if err != nil {
-		el.logErr(err, selector.String())
 		return values.None
 	}
 
-	res, err := NewHtmlElement(el.client, found.NodeID)
+	res, err := LoadElement(el.client, found.NodeID)
 
 	if err != nil {
 		return values.None
@@ -219,14 +232,13 @@ func (el *HtmlElement) QuerySelectorAll(selector values.String) core.Value {
 	res, err := el.client.DOM.QuerySelectorAll(ctx, selectorArgs)
 
 	if err != nil {
-		el.logErr(err, selector.String())
 		return values.None
 	}
 
 	arr := values.NewArray(len(res.NodeIDs))
 
 	for _, id := range res.NodeIDs {
-		childEl, err := NewHtmlElement(el.client, id)
+		childEl, err := LoadElement(el.client, id)
 
 		if err != nil {
 			return values.None
@@ -257,31 +269,37 @@ func (el *HtmlElement) InnerText() values.String {
 }
 
 func (el *HtmlElement) InnerHtml() values.String {
-	ctx, cancelFn := el.createCtx()
+	ctx, cancelFn := createCtx()
 
 	defer cancelFn()
 
 	res, err := el.client.DOM.GetOuterHTML(ctx, dom.NewGetOuterHTMLArgs().SetNodeID(el.id))
 
 	if err != nil {
-		el.logErr(err)
-
 		return values.EmptyString
 	}
 
 	return values.NewString(res.OuterHTML)
 }
 
-func (el *HtmlElement) createCtx() (context.Context, context.CancelFunc) {
+func (el *HtmlElement) Click() (values.Boolean, error) {
+	ctx, cancel := createCtx()
+
+	defer cancel()
+
+	return DispatchEvent(ctx, el.client, el.id, "click")
+}
+
+func createCtx() (context.Context, context.CancelFunc) {
 	return context.WithTimeout(context.Background(), DefaultTimeout)
 }
 
-func (el *HtmlElement) parseAttrs() *values.Object {
+func parseAttrs(attrs []string) *values.Object {
 	var attr values.String
 
 	res := values.NewObject()
 
-	for _, el := range el.node.Attributes {
+	for _, el := range attrs {
 		str := values.NewString(el)
 
 		if common.IsAttribute(el) {
@@ -299,11 +317,18 @@ func (el *HtmlElement) parseAttrs() *values.Object {
 	return res
 }
 
-func (el *HtmlElement) logErr(values ...interface{}) {
-	args := make([]interface{}, 0, len(values)+1)
-	args = append(args, "ERROR:")
-	args = append(args, values...)
-	args = append(args, "id:", el.node.NodeID)
+func loadNodes(client *cdp.Client, nodes []dom.NodeID) *values.Array {
+	arr := values.NewArray(len(nodes))
 
-	log.Println(args...)
+	for _, id := range nodes {
+		child, err := LoadElement(client, id)
+
+		if err != nil {
+			break
+		}
+
+		arr.Push(child)
+	}
+
+	return arr
 }

pkg/stdlib/html/driver/browser/helpers.go

@@ -1,6 +1,16 @@
 package browser
 
-import "golang.org/x/sync/errgroup"
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"github.com/MontFerret/ferret/pkg/runtime/core"
+	"github.com/MontFerret/ferret/pkg/runtime/values"
+	"github.com/mafredri/cdp"
+	"github.com/mafredri/cdp/protocol/dom"
+	"github.com/mafredri/cdp/protocol/runtime"
+	"golang.org/x/sync/errgroup"
+)
 
 func PointerInt(input int) *int {
 	return &input
@@ -17,3 +27,107 @@ func RunBatch(funcs ...BatchFunc) error {
 
 	return eg.Wait()
 }
+
+func PrepareEval(exp string) string {
+	return fmt.Sprintf("((function () {%s})())", exp)
+}
+
+func Eval(client *cdp.Client, exp string, ret bool, async bool) (core.Value, error) {
+	args := runtime.
+		NewEvaluateArgs(PrepareEval(exp)).
+		SetReturnByValue(ret).
+		SetAwaitPromise(async)
+
+	out, err := client.Runtime.Evaluate(context.Background(), args)
+
+	if err != nil {
+		return values.None, err
+	}
+
+	if out.ExceptionDetails != nil {
+		ex := out.ExceptionDetails
+
+		return values.None, core.Error(
+			core.ErrUnexpected,
+			fmt.Sprintf("%s: %s", ex.Text, *ex.Exception.Description),
+		)
+	}
+
+	if out.Result.Type != "undefined" {
+		var o interface{}
+
+		err := json.Unmarshal(out.Result.Value, &o)
+
+		if err != nil {
+			return values.None, core.Error(core.ErrUnexpected, err.Error())
+		}
+
+		return values.Parse(o), nil
+	}
+
+	return values.None, nil
+}
+
+func DispatchEvent(
+	ctx context.Context,
+	client *cdp.Client,
+	id dom.NodeID,
+	eventName string,
+) (values.Boolean, error) {
+	// get a ref to remote object representing the node
+	obj, err := client.DOM.ResolveNode(
+		ctx,
+		dom.NewResolveNodeArgs().
+			SetNodeID(id),
+	)
+
+	if err != nil {
+		return values.False, err
+	}
+
+	if obj.Object.ObjectID == nil {
+		return values.False, nil
+	}
+
+	evt, err := client.Runtime.Evaluate(ctx, runtime.NewEvaluateArgs(PrepareEval(fmt.Sprintf(`
+		return new window.MouseEvent('%s', { bubbles: true })
+	`, eventName))))
+
+	if err != nil {
+		return values.False, nil
+	}
+
+	if evt.ExceptionDetails != nil {
+		return values.False, evt.ExceptionDetails
+	}
+
+	if evt.Result.ObjectID == nil {
+		return values.False, nil
+	}
+
+	evtId := evt.Result.ObjectID
+
+	// release the event object
+	defer client.Runtime.ReleaseObject(ctx, runtime.NewReleaseObjectArgs(*evtId))
+
+	res, err := client.Runtime.CallFunctionOn(
+		ctx,
+		runtime.NewCallFunctionOnArgs("dispatchEvent").
+			SetObjectID(*obj.Object.ObjectID).
+			SetArguments([]runtime.CallArgument{
+				{
+					ObjectID: evt.Result.ObjectID,
+				},
+			}),
+	)
+
+	if err != nil {
+		return values.False, err
+	}
+
+	if res.ExceptionDetails != nil {
+		return values.False, res.ExceptionDetails
+	}
+
+	return values.True, nil
+}

pkg/stdlib/html/driver/browser/wait.go

@@ -1,13 +1,9 @@
 package browser
 
 import (
-	"context"
-	"encoding/json"
-	"fmt"
 	"github.com/MontFerret/ferret/pkg/runtime/core"
 	"github.com/MontFerret/ferret/pkg/runtime/values"
 	"github.com/mafredri/cdp"
-	"github.com/mafredri/cdp/protocol/runtime"
 	"time"
 )
 
@@ -15,82 +11,65 @@ type WaitTask struct {
 	client    *cdp.Client
 	predicate string
 	timeout   time.Duration
+	polling   time.Duration
 }
 
+const DefaultPolling = time.Millisecond * time.Duration(200)
+
 func NewWaitTask(
 	client *cdp.Client,
 	predicate string,
 	timeout time.Duration,
+	polling time.Duration,
 ) *WaitTask {
 	return &WaitTask{
 		client,
-		fmt.Sprintf("((function () {%s})())", predicate),
+		predicate,
 		timeout,
+		polling,
 	}
 }
 
 func (task *WaitTask) Run() (core.Value, error) {
-	var result core.Value = values.None
-	var err error
-	var done bool
 	timer := time.NewTimer(task.timeout)
 
-	for !done {
+	for {
 		select {
 		case <-timer.C:
-			err = core.ErrTimeout
-			done = true
+			return values.None, core.ErrTimeout
 		default:
-			out, e := task.exec()
+			out, err := task.eval()
 
-			if e != nil {
-				done = true
+			// JS expression failed
+			// terminating
+			if err != nil {
 				timer.Stop()
-				err = e
 
-				break
+				return values.None, err
 			}
 
+			// JS output is not empty
+			// terminating
 			if out != values.None {
 				timer.Stop()
 
-				result = out
-				done = true
-				break
+				return out, nil
 			}
+
+			// Nothing yet, let's wait before the next try
+			time.Sleep(task.polling)
 		}
 	}
 
-	return result, err
+	// TODO: Do we need this code?
+	return values.None, core.ErrTimeout
 }
 
-func (task *WaitTask) exec() (core.Value, error) {
-	args := runtime.NewEvaluateArgs(task.predicate).SetReturnByValue(true)
-	out, err := task.client.Runtime.Evaluate(context.Background(), args)
-
-	if err != nil {
-		return values.None, err
-	}
-
-	if out.ExceptionDetails != nil {
-		ex := out.ExceptionDetails
-		return values.None, core.Error(
-			core.ErrUnexpected,
-			fmt.Sprintf("%s %s", ex.Text, *ex.Exception.Description),
-		)
-	}
-
-	if out.Result.Type != "undefined" {
-		var o interface{}
-
-		err := json.Unmarshal(out.Result.Value, &o)
-
-		if err != nil {
-			return values.None, core.Error(core.ErrUnexpected, err.Error())
-		}
-
-		return values.Parse(o), nil
-	}
-
-	return values.None, nil
+func (task *WaitTask) eval() (core.Value, error) {
+	return Eval(
+		task.client,
+		task.predicate,
+		true,
+		false,
+	)
 }

pkg/stdlib/html/events.go

@@ -16,7 +16,7 @@ func WaitElement(_ context.Context, args ...core.Value) (core.Value, error) {
 
 	arg := args[0]
 	selector := args[1].String()
-	timeout := values.NewInt(1000)
+	timeout := values.NewInt(5000)
 
 	if len(args) > 2 {
 		if args[2].Type() == core.IntType {
@@ -30,7 +30,11 @@ func WaitElement(_ context.Context, args ...core.Value) (core.Value, error) {
 		return values.None, err
 	}
 
-	doc := arg.(*browser.HtmlDocument)
+	doc, ok := arg.(*browser.HtmlDocument)
+
+	if !ok {
+		return values.False, core.Error(core.ErrInvalidType, "expected dynamic document")
+	}
 
 	return values.None, doc.WaitForSelector(values.NewString(selector), timeout)
 }

pkg/stdlib/html/lib.go

@@ -9,5 +9,6 @@ func NewLib() map[string]core.Function {
 		"ELEMENT":        Element,
 		"ELEMENTS":       Elements,
 		"WAIT_ELEMENT":   WaitElement,
+		"CLICK":          Click,
 	}
 }

pkg/stdlib/utils/lib.go

@@ -4,7 +4,7 @@ import "github.com/MontFerret/ferret/pkg/runtime/core"
 
 func NewLib() map[string]core.Function {
 	return map[string]core.Function{
-		"SLEEP": Sleep,
-		"LOG":   Log,
+		"WAIT": Wait,
+		"LOG":  Log,
 	}
 }

pkg/stdlib/utils/utils.go

@@ -8,7 +8,7 @@ import (
 	"time"
 )
 
-func Sleep(_ context.Context, inputs ...core.Value) (core.Value, error) {
+func Wait(_ context.Context, inputs ...core.Value) (core.Value, error) {
 	err := core.ValidateArgs(inputs, 1, 1)
 
 	if err != nil {