#27 Added logging

.gitignore

@@ -124,3 +124,4 @@ $RECYCLE.BIN/
 
 vendor
 bin
+*.log

Gopkg.lock

@@ -41,6 +41,14 @@
   pruneopts = "UT"
   revision = "2b8494104d86337cdd41d0a49cbed8e4583c0ab4"
 
+[[projects]]
+  digest = "1:ce579162ae1341f3e5ab30c0dce767f28b1eb6a81359aad01723f1ba6b4becdf"
+  name = "github.com/gofrs/uuid"
+  packages = ["."]
+  pruneopts = "UT"
+  revision = "370558f003bfe29580cd0f698d8640daccdcc45c"
+  version = "v3.1.1"
+
 [[projects]]
   branch = "master"
   digest = "1:f14d1b50e0075fb00177f12a96dd7addf93d1e2883c25befd17285b779549795"
@@ -121,6 +129,14 @@
   revision = "75b0ecc5efcff27ac756a33ec71f0db75dc3d21c"
   version = "v0.19.0"
 
+[[projects]]
+  digest = "1:c805e517269b0ba4c21ded5836019ed7d16953d4026cb7d00041d039c7906be9"
+  name = "github.com/natefinch/lumberjack"
+  packages = ["."]
+  pruneopts = "UT"
+  revision = "a96e63847dc3c67d17befa69c303767e2f84e54f"
+  version = "v2.1"
+
 [[projects]]
   digest = "1:40e195917a951a8bf867cd05de2a46aaf1806c50cf92eebf4c16f78cd196f747"
   name = "github.com/pkg/errors"
@@ -129,6 +145,18 @@
   revision = "645ef00459ed84a119197bfb8d8205042c6df63d"
   version = "v0.8.0"
 
+[[projects]]
+  digest = "1:5bc8f93f977b72a7a5264725c3bab275e69de0cc3e5c0dc1ee56feb564c33f03"
+  name = "github.com/rs/zerolog"
+  packages = [
+    ".",
+    "internal/cbor",
+    "internal/json",
+  ]
+  pruneopts = "UT"
+  revision = "338f9bc14084d22cb8eeacd6492861f8449d715c"
+  version = "v1.9.1"
+
 [[projects]]
   digest = "1:4ca145a665316d3c020a39c0741780fa3636b9152b824206796c4dce541f4a24"
   name = "github.com/sethgrid/pester"
@@ -189,6 +217,7 @@
     "github.com/antlr/antlr4/runtime/Go/antlr",
     "github.com/chzyer/readline",
     "github.com/corpix/uarand",
+    "github.com/gofrs/uuid",
     "github.com/mafredri/cdp",
     "github.com/mafredri/cdp/devtool",
     "github.com/mafredri/cdp/protocol/dom",
@@ -198,7 +227,9 @@
     "github.com/mafredri/cdp/protocol/target",
     "github.com/mafredri/cdp/rpcc",
     "github.com/mafredri/cdp/session",
+    "github.com/natefinch/lumberjack",
     "github.com/pkg/errors",
+    "github.com/rs/zerolog",
     "github.com/sethgrid/pester",
     "github.com/smartystreets/goconvey/convey",
     "golang.org/x/net/html",

Gopkg.toml

@@ -44,3 +44,7 @@
 [[constraint]]
   name = "github.com/PuerkitoBio/goquery"
   version = "1.4.1"
+
+[[constraint]]
+  name = "github.com/gofrs/uuid"
+  version = "3.1.1"

cmd/cli/exec.go

@@ -5,8 +5,11 @@ import (
 	"fmt"
 	"github.com/MontFerret/ferret/pkg/compiler"
 	"github.com/MontFerret/ferret/pkg/runtime"
+	"github.com/MontFerret/ferret/pkg/runtime/logging"
 	"io/ioutil"
 	"os"
+	"os/signal"
+	"syscall"
 )
 
 func ExecFile(pathToFile string, opts Options) {
@@ -33,9 +36,25 @@ func Exec(query string, opts Options) {
 		return
 	}
 
+	l := NewLogger()
+
+	ctx, cancel := context.WithCancel(context.Background())
+	c := make(chan os.Signal, 1)
+	signal.Notify(c, syscall.SIGHUP)
+
+	go func() {
+		for {
+			<-c
+			cancel()
+			l.Close()
+		}
+	}()
+
 	out, err := prog.Run(
-		context.Background(),
+		ctx,
 		runtime.WithBrowser(opts.Cdp),
+		runtime.WithLog(l),
+		runtime.WithLogLevel(logging.DebugLevel),
 	)
 
 	if err != nil {

cmd/cli/logger.go

@@ -0,0 +1,14 @@
+package cli
+
+import (
+	"github.com/natefinch/lumberjack"
+)
+
+func NewLogger() *lumberjack.Logger {
+	l := &lumberjack.Logger{
+		Filename: "./ferret.log",
+		MaxSize:  100,
+	}
+
+	return l
+}

cmd/cli/repl.go

@@ -5,8 +5,12 @@ import (
 	"fmt"
 	"github.com/MontFerret/ferret/pkg/compiler"
 	"github.com/MontFerret/ferret/pkg/runtime"
+	"github.com/MontFerret/ferret/pkg/runtime/logging"
 	"github.com/chzyer/readline"
+	"os"
+	"os/signal"
 	"strings"
+	"syscall"
 )
 
 func Repl(version string, opts Options) {
@@ -32,6 +36,20 @@ func Repl(version string, opts Options) {
 
 	timer := NewTimer()
 
+	l := NewLogger()
+
+	ctx, cancel := context.WithCancel(context.Background())
+	c := make(chan os.Signal, 1)
+	signal.Notify(c, syscall.SIGHUP)
+
+	go func() {
+		for {
+			<-c
+			cancel()
+			l.Close()
+		}
+	}()
+
 	for {
 		line, err := rl.Readline()
 
@@ -75,8 +93,10 @@ func Repl(version string, opts Options) {
 		timer.Start()
 
 		out, err := program.Run(
-			context.Background(),
+			ctx,
 			runtime.WithBrowser(opts.Cdp),
+			runtime.WithLog(l),
+			runtime.WithLogLevel(logging.DebugLevel),
 		)
 
 		timer.Stop()

cmd/main.go

@@ -27,7 +27,7 @@ var (
 
 	conn = flag.String(
 		"cdp",
-		"http://127.0.0.1:9222",
+		"http://0.0.0.0:9222",
 		"set CDP address",
 	)
 

docs/examples/test.fql

@@ -1,9 +0,0 @@
-LET g = DOCUMENT("https://www.google.com/", true)
-
-INPUT(ELEMENT(g, 'input[name="q"]'), "ferret")
-
-CLICK(g, 'input[name="btnK"]')
-
-WAIT_NAVIGATION(g)
-
-RETURN 1

pkg/compiler/compiler.go

@@ -78,7 +78,7 @@ func (c *FqlCompiler) Compile(query string) (program *runtime.Program, err error
 		}
 	}()
 
-	l := newVisitor(c.funcs)
+	l := newVisitor(query, c.funcs)
 
 	res := p.Visit(l).(*result)
 

pkg/compiler/compiler_test.go

@@ -1688,39 +1688,24 @@ func TestForTernaryExpression(t *testing.T) {
 	})
 }
 
-//func TestHtml(t *testing.T) {
+func TestHtml(t *testing.T) {
-//	Convey("Should load a document", t, func() {
+	Convey("Should load a document", t, func() {
-//		c := compiler.New()
+		c := compiler.New()
-//
+
-//		prog, err := c.Compile(`
+		out, err := c.MustCompile(`
-//LET doc = DOCUMENT('https://soundcloud.com/charts/top', true)
+LET doc = DOCUMENT("https://github.com/", true)
-//
+LET btn = ELEMENT(doc, ".HeaderMenu a")
-//// TODO: We need a better way of waiting for page loading
+
-//// Something line WAIT_FOR(doc, selector)
+CLICK(btn)
-//SLEEP(2000)
+WAIT_NAVIGATION(doc)
-//
+WAIT_ELEMENT(doc, '.IconNav')
-//LET tracks = ELEMENTS(doc, '.chartTrack__details')
+
-//
+RETURN INNER_HTML_ALL(doc, '.IconNav a')
-//LOG("found", LENGTH(tracks), "tracks")
+
-//
+		`).Run(context.Background())
-//FOR track IN tracks
+
-//    // LET username = ELEMENT(track, '.chartTrack__username')
+		So(err, ShouldBeNil)
-//    // LET title = ELEMENT(track, '.chartTrack__title')
+
-//
+		So(string(out), ShouldEqual, `"int"`)
-//    // LOG("NODE", track.nodeName)
+	})
-//
+}
-//    SLEEP(500)
-//
-//    RETURN track.innerHtml
-//
-//		`)
-//
-//		So(err, ShouldBeNil)
-//
-//		out, err := prog.Run(context.Background(), runtime.WithBrowser("http://127.0.0.1:9222"))
-//
-//		So(err, ShouldBeNil)
-//
-//		So(string(out), ShouldEqual, `"int"`)
-//	})
-//}

pkg/compiler/visitor.go

@@ -18,13 +18,14 @@ import (
 
 type visitor struct {
 	*fql.BaseFqlParserVisitor
-
+	src   string
 	funcs map[string]core.Function
 }
 
-func newVisitor(funcs map[string]core.Function) *visitor {
+func newVisitor(src string, funcs map[string]core.Function) *visitor {
 	return &visitor{
 		&fql.BaseFqlParserVisitor{},
+		src,
 		funcs,
 	}
 }
@@ -38,7 +39,7 @@ func (v *visitor) VisitProgram(ctx *fql.ProgramContext) interface{} {
 			return nil, err
 		}
 
-		return runtime.NewProgram(block), nil
+		return runtime.NewProgram(v.src, block)
 	})
 }
 

pkg/runtime/logging/logger.go

@@ -0,0 +1,23 @@
+package logging
+
+import (
+	"context"
+	"github.com/rs/zerolog"
+)
+
+type Level uint8
+
+const (
+	DebugLevel Level = iota
+	InfoLevel
+	WarnLevel
+	ErrorLevel
+	FatalLevel
+	PanicLevel
+	NoLevel
+	Disabled
+)
+
+func From(ctx context.Context) *zerolog.Logger {
+	return zerolog.Ctx(ctx)
+}

pkg/runtime/options.go

@@ -1,12 +1,21 @@
 package runtime
 
-import "context"
+import (
+	"context"
+	"github.com/MontFerret/ferret/pkg/runtime/logging"
+	"github.com/gofrs/uuid"
+	"github.com/rs/zerolog"
+	"io"
+	"os"
+)
 
 type (
 	Options struct {
 		proxy     string
 		cdp       string
 		variables map[string]interface{}
+		logWriter io.Writer
+		logLevel  zerolog.Level
 	}
 
 	Option func(*Options)
@@ -14,8 +23,10 @@ type (
 
 func newOptions() *Options {
 	return &Options{
-		cdp:       "http://127.0.0.1:9222",
+		cdp:       "http://0.0.0.0:9222",
 		variables: make(map[string]interface{}),
+		logWriter: os.Stdout,
+		logLevel:  zerolog.ErrorLevel,
 	}
 }
 
@@ -38,10 +49,38 @@ func WithProxy(address string) Option {
 	}
 }
 
+func WithLog(writer io.Writer) Option {
+	return func(options *Options) {
+		options.logWriter = writer
+	}
+}
+
+func WithLogLevel(lvl logging.Level) Option {
+	return func(options *Options) {
+		options.logLevel = zerolog.Level(lvl)
+	}
+}
+
 func (opts *Options) withContext(parent context.Context) context.Context {
-	return context.WithValue(
+	ctx := context.WithValue(
 		parent,
 		"variables",
 		opts.variables,
 	)
+
+	id, err := uuid.NewV4()
+
+	if err != nil {
+		panic(err)
+	}
+
+	logger := zerolog.New(opts.logWriter).
+		With().
+		Str("id", id.String()).
+		Logger()
+	logger.WithLevel(opts.logLevel)
+
+	ctx = logger.WithContext(ctx)
+
+	return ctx
 }

pkg/runtime/program.go

@@ -8,11 +8,24 @@ import (
 )
 
 type Program struct {
-	exp core.Expression
+	src  string
+	body core.Expression
 }
 
-func NewProgram(exp core.Expression) *Program {
+func NewProgram(src string, body core.Expression) (*Program, error) {
-	return &Program{exp}
+	if src == "" {
+		return nil, core.Error(core.ErrMissedArgument, "source")
+	}
+
+	if core.IsNil(body) {
+		return nil, core.Error(core.ErrMissedArgument, "body")
+	}
+
+	return &Program{src, body}, nil
+}
+
+func (p *Program) Source() string {
+	return p.src
 }
 
 func (p *Program) Run(ctx context.Context, setters ...Option) ([]byte, error) {
@@ -30,7 +43,7 @@ func (p *Program) Run(ctx context.Context, setters ...Option) ([]byte, error) {
 	ctx = driver.WithDynamicDriver(ctx, opts.cdp)
 	ctx = driver.WithStaticDriver(ctx)
 
-	out, err := p.exp.Exec(ctx, scope)
+	out, err := p.body.Exec(ctx, scope)
 
 	if err != nil {
 		js, _ := values.None.MarshalJSON()

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

@@ -5,6 +5,7 @@ import (
 	"crypto/sha512"
 	"fmt"
 	"github.com/MontFerret/ferret/pkg/runtime/core"
+	"github.com/MontFerret/ferret/pkg/runtime/logging"
 	"github.com/MontFerret/ferret/pkg/runtime/values"
 	"github.com/MontFerret/ferret/pkg/stdlib/html/driver/dynamic/eval"
 	"github.com/MontFerret/ferret/pkg/stdlib/html/driver/dynamic/events"
@@ -15,12 +16,14 @@ import (
 	"github.com/mafredri/cdp/protocol/page"
 	"github.com/mafredri/cdp/rpcc"
 	"github.com/pkg/errors"
+	"github.com/rs/zerolog"
 	"sync"
 	"time"
 )
 
 type HtmlDocument struct {
 	sync.Mutex
+	logger  *zerolog.Logger
 	conn    *rpcc.Conn
 	client  *cdp.Client
 	events  *events.EventBroker
@@ -93,7 +96,14 @@ func LoadHtmlDocument(
 		return nil, err
 	}
 
-	return NewHtmlDocument(conn, client, broker, root, innerHtml), nil
+	return NewHtmlDocument(
+		logging.From(ctx),
+		conn,
+		client,
+		broker,
+		root,
+		innerHtml,
+	), nil
 }
 
 func getRootElement(client *cdp.Client) (dom.Node, values.String, error) {
@@ -117,6 +127,7 @@ func getRootElement(client *cdp.Client) (dom.Node, values.String, error) {
 }
 
 func NewHtmlDocument(
+	logger *zerolog.Logger,
 	conn *rpcc.Conn,
 	client *cdp.Client,
 	broker *events.EventBroker,
@@ -124,10 +135,11 @@ func NewHtmlDocument(
 	innerHtml values.String,
 ) *HtmlDocument {
 	doc := new(HtmlDocument)
+	doc.logger = logger
 	doc.conn = conn
 	doc.client = client
 	doc.events = broker
-	doc.element = NewHtmlElement(client, broker, root.NodeID, root, innerHtml)
+	doc.element = NewHtmlElement(doc.logger, client, broker, root.NodeID, root, innerHtml)
 	doc.url = ""
 
 	if root.BaseURL != nil {
@@ -141,7 +153,11 @@ func NewHtmlDocument(
 		updated, innerHtml, err := getRootElement(client)
 
 		if err != nil {
-			// TODO: We need somehow log all errors outside of stdout
+			doc.logger.Error().
+				Timestamp().
+				Err(err).
+				Msg("failed to get root node after page load")
+
 			return
 		}
 
@@ -149,7 +165,7 @@ func NewHtmlDocument(
 		doc.element.Close()
 
 		// create a new root element wrapper
-		doc.element = NewHtmlElement(client, broker, updated.NodeID, updated, innerHtml)
+		doc.element = NewHtmlElement(doc.logger, client, broker, updated.NodeID, updated, innerHtml)
 		doc.url = ""
 
 		if updated.BaseURL != nil {
@@ -226,11 +242,47 @@ func (doc *HtmlDocument) Close() error {
 	doc.Lock()
 	defer doc.Unlock()
 
-	doc.events.Stop()
+	var err error
-	doc.events.Close()
 
-	doc.element.Close()
+	err = doc.events.Stop()
-	doc.client.Page.Close(context.Background())
+
+	if err != nil {
+		doc.logger.Warn().
+			Timestamp().
+			Str("url", doc.url.String()).
+			Err(err).
+			Msg("failed to stop event broker")
+	}
+
+	err = doc.events.Close()
+
+	if err != nil {
+		doc.logger.Warn().
+			Timestamp().
+			Str("url", doc.url.String()).
+			Err(err).
+			Msg("failed to close event broker")
+	}
+
+	err = doc.element.Close()
+
+	if err != nil {
+		doc.logger.Warn().
+			Timestamp().
+			Str("url", doc.url.String()).
+			Err(err).
+			Msg("failed to close root element")
+	}
+
+	err = doc.client.Page.Close(context.Background())
+
+	if err != nil {
+		doc.logger.Warn().
+			Timestamp().
+			Str("url", doc.url.String()).
+			Err(err).
+			Msg("failed to close browser page")
+	}
 
 	return doc.conn.Close()
 }
@@ -354,13 +406,18 @@ func (doc *HtmlDocument) InnerHtmlBySelectorAll(selector values.String) (*values
 	res, err := eval.Eval(
 		doc.client,
 		fmt.Sprintf(`
+			var result = [];
 			var elements = document.querySelectorAll(%s);
 
 			if (elements == null) {
-				return [];
+				return result;
 			}
 
-			return elements.map(i => i.innerHtml);
+			elements.forEach((i) => {
+				result.push(i.innerHtml);
+			});
+
+			return result;
 		`, eval.ParamString(selector.String())),
 		true,
 		false,
@@ -408,13 +465,18 @@ func (doc *HtmlDocument) InnerTextBySelectorAll(selector values.String) (*values
 	res, err := eval.Eval(
 		doc.client,
 		fmt.Sprintf(`
+			var result = [];
 			var elements = document.querySelectorAll(%s);
 
 			if (elements == null) {
-				return [];
+				return result;
 			}
 
-			return elements.map(i => i.innerText);
+			elements.forEach((i) => {
+				result.push(i.innerText);
+			});
+
+			return result;
 		`, eval.ParamString(selector.String())),
 		true,
 		false,

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

@@ -13,6 +13,7 @@ import (
 	"github.com/PuerkitoBio/goquery"
 	"github.com/mafredri/cdp"
 	"github.com/mafredri/cdp/protocol/dom"
+	"github.com/rs/zerolog"
 	"strconv"
 	"sync"
 	"time"
@@ -22,6 +23,7 @@ const DefaultTimeout = time.Second * 30
 
 type HtmlElement struct {
 	sync.Mutex
+	logger         *zerolog.Logger
 	client         *cdp.Client
 	broker         *events.EventBroker
 	connected      values.Boolean
@@ -31,12 +33,14 @@ type HtmlElement struct {
 	innerHtml      values.String
 	innerText      *common.LazyValue
 	value          core.Value
+	rawAttrs       []string
 	attributes     *common.LazyValue
 	children       []dom.NodeID
 	loadedChildren *common.LazyValue
 }
 
 func LoadElement(
+	logger *zerolog.Logger,
 	client *cdp.Client,
 	broker *events.EventBroker,
 	id dom.NodeID,
@@ -68,6 +72,7 @@ func LoadElement(
 	}
 
 	return NewHtmlElement(
+		logger,
 		client,
 		broker,
 		id,
@@ -77,6 +82,7 @@ func LoadElement(
 }
 
 func NewHtmlElement(
+	logger *zerolog.Logger,
 	client *cdp.Client,
 	broker *events.EventBroker,
 	id dom.NodeID,
@@ -84,6 +90,7 @@ func NewHtmlElement(
 	innerHtml values.String,
 ) *HtmlElement {
 	el := new(HtmlElement)
+	el.logger = logger
 	el.client = client
 	el.broker = broker
 	el.connected = values.True
@@ -91,34 +98,11 @@ func NewHtmlElement(
 	el.nodeType = values.NewInt(node.NodeType)
 	el.nodeName = values.NewString(node.NodeName)
 	el.innerHtml = innerHtml
-	el.innerText = common.NewLazyValue(func() (core.Value, error) {
+	el.innerText = common.NewLazyValue(el.loadInnerText)
-		h := el.InnerHtml()
+	el.rawAttrs = node.Attributes[:]
-
+	el.attributes = common.NewLazyValue(el.loadAttrs)
-		if h == values.EmptyString {
-			return h, nil
-		}
-
-		buff := bytes.NewBuffer([]byte(h))
-
-		parsed, err := goquery.NewDocumentFromReader(buff)
-
-		if err != nil {
-			return values.EmptyString, err
-		}
-
-		return values.NewString(parsed.Text()), nil
-	})
-	el.attributes = common.NewLazyValue(func() (core.Value, error) {
-		return parseAttrs(node.Attributes), nil
-	})
 	el.value = values.EmptyString
-	el.loadedChildren = common.NewLazyValue(func() (core.Value, error) {
+	el.loadedChildren = common.NewLazyValue(el.loadChildren)
-		if !el.IsConnected() {
-			return values.NewArray(0), nil
-		}
-
-		return loadNodes(client, broker, el.children)
-	})
 
 	if node.Value != nil {
 		el.value = values.NewString(*node.Value)
@@ -205,11 +189,19 @@ func (el *HtmlElement) Unwrap() interface{} {
 }
 
 func (el *HtmlElement) Hash() int {
+	el.Lock()
+	defer el.Unlock()
+
 	h := sha512.New()
 
-	out, err := h.Write([]byte(strconv.Itoa(int(el.id))))
+	out, err := h.Write([]byte(el.innerHtml))
 
 	if err != nil {
+		el.logger.Error().
+			Timestamp().
+			Err(err).
+			Msg("failed to calculate hash value")
+
 		return 0
 	}
 
@@ -227,6 +219,11 @@ func (el *HtmlElement) Value() core.Value {
 	val, err := eval.Property(ctx, el.client, el.id, "value")
 
 	if err != nil {
+		el.logger.Error().
+			Timestamp().
+			Err(err).
+			Msg("failed to get node value")
+
 		return el.value
 	}
 
@@ -309,12 +306,24 @@ func (el *HtmlElement) QuerySelector(selector values.String) core.Value {
 	found, err := el.client.DOM.QuerySelector(ctx, selectorArgs)
 
 	if err != nil {
+		el.logger.Error().
+			Timestamp().
+			Str("selector", selector.String()).
+			Err(err).
+			Msg("failed to retrieve a node by selector")
+
 		return values.None
 	}
 
-	res, err := LoadElement(el.client, el.broker, found.NodeID)
+	res, err := LoadElement(el.logger, el.client, el.broker, found.NodeID)
 
 	if err != nil {
+		el.logger.Error().
+			Timestamp().
+			Str("selector", selector.String()).
+			Err(err).
+			Msg("failed to load a child node by selector")
+
 		return values.None
 	}
 
@@ -332,15 +341,27 @@ func (el *HtmlElement) QuerySelectorAll(selector values.String) core.Value {
 	res, err := el.client.DOM.QuerySelectorAll(ctx, selectorArgs)
 
 	if err != nil {
+		el.logger.Error().
+			Timestamp().
+			Str("selector", selector.String()).
+			Err(err).
+			Msg("failed to retrieve nodes by selector")
+
 		return values.None
 	}
 
 	arr := values.NewArray(len(res.NodeIDs))
 
 	for _, id := range res.NodeIDs {
-		childEl, err := LoadElement(el.client, el.broker, id)
+		childEl, err := LoadElement(el.logger, el.client, el.broker, id)
 
 		if err != nil {
+			el.logger.Error().
+				Timestamp().
+				Str("selector", selector.String()).
+				Err(err).
+				Msg("failed to load nodes by selector")
+
 			return values.None
 		}
 
@@ -389,6 +410,54 @@ func (el *HtmlElement) IsConnected() values.Boolean {
 	return el.connected
 }
 
+func (el *HtmlElement) loadInnerText() (core.Value, error) {
+	h := el.InnerHtml()
+
+	if h == values.EmptyString {
+		return h, nil
+	}
+
+	buff := bytes.NewBuffer([]byte(h))
+
+	parsed, err := goquery.NewDocumentFromReader(buff)
+
+	if err != nil {
+		el.logger.Error().
+			Timestamp().
+			Err(err).
+			Int("id", int(el.id)).
+			Msg("failed to parse inner html")
+
+		return values.EmptyString, err
+	}
+
+	return values.NewString(parsed.Text()), nil
+}
+
+func (el *HtmlElement) loadAttrs() (core.Value, error) {
+	return parseAttrs(el.rawAttrs), nil
+}
+
+func (el *HtmlElement) loadChildren() (core.Value, error) {
+	if !el.IsConnected() {
+		return values.NewArray(0), nil
+	}
+
+	loaded, err := loadNodes(el.logger, el.client, el.broker, el.children)
+
+	if err != nil {
+		el.logger.Error().
+			Timestamp().
+			Err(err).
+			Int("id", int(el.id)).
+			Msg("failed to load child nodes")
+
+		return values.None, err
+	}
+
+	return loaded, nil
+}
+
 func (el *HtmlElement) handlePageReload(message interface{}) {
 	el.Close()
 }
@@ -484,6 +553,12 @@ func (el *HtmlElement) handleChildrenCountChanged(message interface{}) {
 	node, err := el.client.DOM.DescribeNode(context.Background(), dom.NewDescribeNodeArgs())
 
 	if err != nil {
+		el.logger.Error().
+			Timestamp().
+			Err(err).
+			Int("id", int(el.id)).
+			Msg("failed to update node")
+
 		return
 	}
 
@@ -536,10 +611,15 @@ func (el *HtmlElement) handleChildInserted(message interface{}) {
 	}
 
 	loadedArr := loaded.(*values.Array)
-
+	loadedEl, err := LoadElement(el.logger, el.client, el.broker, nextId)
-	loadedEl, err := LoadElement(el.client, el.broker, nextId)
 
 	if err != nil {
+		el.logger.Error().
+			Timestamp().
+			Err(err).
+			Int("id", int(el.id)).
+			Msg("failed to load an inserted node")
+
 		return
 	}
 
@@ -548,6 +628,12 @@ func (el *HtmlElement) handleChildInserted(message interface{}) {
 	newInnerHtml, err := loadInnerHtml(el.client, el.id)
 
 	if err != nil {
+		el.logger.Error().
+			Timestamp().
+			Err(err).
+			Int("id", int(el.id)).
+			Msg("failed to update node")
+
 		return
 	}
 
@@ -601,6 +687,12 @@ func (el *HtmlElement) handleChildDeleted(message interface{}) {
 	newInnerHtml, err := loadInnerHtml(el.client, el.id)
 
 	if err != nil {
+		el.logger.Error().
+			Timestamp().
+			Err(err).
+			Int("id", int(el.id)).
+			Msg("failed to update node")
+
 		return
 	}
 

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

@@ -8,6 +8,7 @@ import (
 	"github.com/mafredri/cdp"
 	"github.com/mafredri/cdp/protocol/dom"
 	"github.com/mafredri/cdp/protocol/page"
+	"github.com/rs/zerolog"
 	"golang.org/x/sync/errgroup"
 )
 
@@ -70,11 +71,11 @@ func createChildrenArray(nodes []dom.Node) []dom.NodeID {
 	return children
 }
 
-func loadNodes(client *cdp.Client, broker *events.EventBroker, nodes []dom.NodeID) (*values.Array, error) {
+func loadNodes(logger *zerolog.Logger, client *cdp.Client, broker *events.EventBroker, nodes []dom.NodeID) (*values.Array, error) {
 	arr := values.NewArray(len(nodes))
 
 	for _, id := range nodes {
-		child, err := LoadElement(client, broker, id)
+		child, err := LoadElement(logger, client, broker, id)
 
 		if err != nil {
 			return nil, err

pkg/stdlib/utils/utils.go

@@ -3,8 +3,8 @@ package utils
 import (
 	"context"
 	"github.com/MontFerret/ferret/pkg/runtime/core"
+	"github.com/MontFerret/ferret/pkg/runtime/logging"
 	"github.com/MontFerret/ferret/pkg/runtime/values"
-	"log"
 	"time"
 )
 
@@ -30,16 +30,16 @@ func Wait(_ context.Context, inputs ...core.Value) (core.Value, error) {
 	return values.None, nil
 }
 
-func Log(_ context.Context, inputs ...core.Value) (core.Value, error) {
+func Log(ctx context.Context, inputs ...core.Value) (core.Value, error) {
 	args := make([]interface{}, 0, len(inputs)+1)
 
-	args = append(args, "LOG:")
-
 	for _, input := range inputs {
 		args = append(args, input)
 	}
 
-	log.Println(args...)
+	logger := logging.From(ctx)
+
+	logger.Print(args...)
 
 	return values.None, nil
 }