diff --git a/cmd/run.go b/cmd/run.go
index 2290e432407..66a798d3fed 100644
--- a/cmd/run.go
+++ b/cmd/run.go
@@ -190,7 +190,7 @@ func (c *cmdRun) run(cmd *cobra.Command, args []string) (err error) {
 	if !testRunState.RuntimeOptions.NoSummary.Bool {
 		defer func() {
 			logger.Debug("Generating the end-of-test summary...")
-			summaryResult, hsErr := test.initRunner.HandleSummary(globalCtx, &lib.Summary{
+			summaryResult, summaryJs, hsErr := test.initRunner.HandleSummary(globalCtx, &lib.Summary{
 				Metrics:         metricsEngine.ObservedMetrics,
 				RootGroup:       testRunState.Runner.GetDefaultGroup(),
 				TestRunDuration: executionState.GetCurrentTestRunDuration(),
@@ -204,7 +204,7 @@ func (c *cmdRun) run(cmd *cobra.Command, args []string) (err error) {
 				hsErr = handleSummaryResult(c.gs.FS, c.gs.Stdout, c.gs.Stderr, summaryResult)
 				waitForSummaryGeneratedEvent := emitEvent(&event.Event{
 					Type: event.TestSummaryGenerated,
-					Data: &event.SummaryData{Summary: summaryResult},
+					Data: &event.SummaryData{Summary: summaryJs},
 				})
 				waitForSummaryGeneratedEvent()
 			}
diff --git a/event/type.go b/event/type.go
index 8755ddea131..dcc4bdc0a7e 100644
--- a/event/type.go
+++ b/event/type.go
@@ -1,6 +1,5 @@
 package event
 
-import "io"
 
 // Type represents the different event types emitted by k6.
 //
@@ -48,5 +47,5 @@ type IterData struct {
 
 // SummaryData is the data sent in the TestSummaryGenerated event.
 type SummaryData struct {
-	Summary map[string]io.Reader
+	Summary map[string]interface{}
 }
diff --git a/js/runner.go b/js/runner.go
index aae07f7a9ed..a704debed1c 100644
--- a/js/runner.go
+++ b/js/runner.go
@@ -362,7 +362,7 @@ func (r *Runner) IsExecutable(name string) bool {
 }
 
 // HandleSummary calls the specified summary callback, if supplied.
-func (r *Runner) HandleSummary(ctx context.Context, summary *lib.Summary) (map[string]io.Reader, error) {
+func (r *Runner) HandleSummary(ctx context.Context, summary *lib.Summary) (map[string]io.Reader,map[string]interface{}, error) {
 	summaryDataForJS := summarizeMetricsToObject(summary, r.Bundle.Options, r.setupData)
 
 	out := make(chan metrics.SampleContainer, 100)
@@ -378,7 +378,7 @@ func (r *Runner) HandleSummary(ctx context.Context, summary *lib.Summary) (map[s
 
 	vu, err := r.newVU(summaryCtx, 0, 0, out)
 	if err != nil {
-		return nil, err
+		return nil,nil, err
 	}
 
 	go func() {
@@ -392,7 +392,7 @@ func (r *Runner) HandleSummary(ctx context.Context, summary *lib.Summary) (map[s
 	if fn != nil {
 		handleSummaryFn, ok := goja.AssertFunction(fn)
 		if !ok {
-			return nil, fmt.Errorf("exported identifier %s must be a function", consts.HandleSummaryFn)
+			return nil,nil, fmt.Errorf("exported identifier %s must be a function", consts.HandleSummaryFn)
 		}
 
 		callbackResult, _, _, err = vu.runFn(summaryCtx, false, handleSummaryFn, nil, vu.Runtime.ToValue(summaryDataForJS))
@@ -405,11 +405,11 @@ func (r *Runner) HandleSummary(ctx context.Context, summary *lib.Summary) (map[s
 	wrapper := strings.Replace(summaryWrapperLambdaCode, "/*JSLIB_SUMMARY_CODE*/", jslibSummaryCode, 1)
 	handleSummaryWrapperRaw, err := vu.Runtime.RunString(wrapper)
 	if err != nil {
-		return nil, fmt.Errorf("unexpected error while getting the summary wrapper: %w", err)
+		return nil,nil, fmt.Errorf("unexpected error while getting the summary wrapper: %w", err)
 	}
 	handleSummaryWrapper, ok := goja.AssertFunction(handleSummaryWrapperRaw)
 	if !ok {
-		return nil, fmt.Errorf("unexpected error did not get a callable summary wrapper")
+		return nil,nil, fmt.Errorf("unexpected error did not get a callable summary wrapper")
 	}
 
 	wrapperArgs := []goja.Value{
@@ -420,13 +420,14 @@ func (r *Runner) HandleSummary(ctx context.Context, summary *lib.Summary) (map[s
 	rawResult, _, _, err := vu.runFn(summaryCtx, false, handleSummaryWrapper, nil, wrapperArgs...)
 
 	if deadlineError := r.checkDeadline(summaryCtx, consts.HandleSummaryFn, rawResult, err); deadlineError != nil {
-		return nil, deadlineError
+		return nil,nil, deadlineError
 	}
 
 	if err != nil {
-		return nil, fmt.Errorf("unexpected error while generating the summary: %w", err)
+		return nil,nil, fmt.Errorf("unexpected error while generating the summary: %w", err)
 	}
-	return getSummaryResult(rawResult)
+	res, err := getSummaryResult(rawResult)
+	return res,summaryDataForJS, err
 }
 
 func (r *Runner) checkDeadline(ctx context.Context, name string, result goja.Value, err error) error {
diff --git a/lib/runner.go b/lib/runner.go
index 92bad4a22f2..b89d8e6bc1e 100644
--- a/lib/runner.go
+++ b/lib/runner.go
@@ -86,7 +86,7 @@ type Runner interface {
 	// function in the script.
 	IsExecutable(string) bool
 
-	HandleSummary(context.Context, *Summary) (map[string]io.Reader, error)
+	HandleSummary(context.Context, *Summary) (map[string]io.Reader, map[string]interface{}, error)
 }
 
 // UIState describes the state of the UI, which might influence what