Gracefully handle NaN and Inf values (#21)

4 files changed, 72 insertions, 13 deletions

diff --git a/js.go b/js.go
index 719c031..0fef6dc 100644
--- a/js.go
+++ b/js.go
@@ -135,22 +135,29 @@ func vm(src string, imports Imports) (Exports, error) {
 		exports[key] = obj.Get(key).Export()
 	}
 
-	exports["__scrape"] = scrape(vm)
+	exports["__scrape"], err = scrape(vm)
+	if err != nil {
+		return nil, err
+	}
 
 	return exports, nil
 }
 
-func scrape(vm *goja.Runtime) ScrapeFunc {
+func scrape(vm *goja.Runtime) (ScrapeFunc, error) {
 	var lock sync.Mutex
 
-	defaultfn, err := vm.RunString("module.exports.default")
+	if v, err := vm.RunString("module.exports.default"); err != nil || goja.IsUndefined(v) {
+		return nil, errors.New("default export is not defined")
+	}
+
+	defaultfn, err := vm.RunString("(o) => JSON.stringify(module.exports.default(o))")
 	if err != nil {
-		return func(ScrapeParams) (any, error) { return nil, errors.New("no scrape function defined") }
+		return nil, fmt.Errorf("failed to create scrape function: %w", err)
 	}
 
 	scrapefn, ok := defaultfn.Export().(func(goja.FunctionCall) goja.Value)
 	if !ok {
-		return func(ScrapeParams) (any, error) { return nil, errors.New("default export is not a function") }
+		return nil, errors.New("failed to export scrape funtion")
 	}
 
 	return func(p ScrapeParams) (any, error) {
@@ -183,9 +190,19 @@ func scrape(vm *goja.Runtime) ScrapeFunc {
 		o.Set("doc", doc)
 		o.Set("absoluteURL", absoluteURL)
 
-		ret := scrapefn(goja.FunctionCall{Arguments: []goja.Value{o}}).Export()
-		return ret, nil
-	}
+		ret := scrapefn(goja.FunctionCall{Arguments: []goja.Value{o}})
+		if goja.IsUndefined(ret) {
+			return nil, nil
+		}
+
+		var result any
+		if err := json.Unmarshal([]byte(ret.String()), &result); err != nil {
+			log.Println(err)
+			return nil, err
+		}
+
+		return result, nil
+	}, nil
 }
 
 func DocumentFromString(s string) (map[string]any, error) {
diff --git a/js_lib_test.go b/js_lib_test.go
index e375308..20e39da 100644
--- a/js_lib_test.go
+++ b/js_lib_test.go
@@ -20,6 +20,8 @@ func TestJSLibParse(t *testing.T) {
 
     const doc = parse('<div class=foo>Hello world</div>')
     export const text = doc.find(".foo").text()
+
+    export default function () {}
     `
 
 	client := &http.Client{
@@ -45,6 +47,8 @@ func TestJSLibHTTPGet(t *testing.T) {
     export const status = res.status;
     export const error = res.error;
     export const headers = res.headers;
+
+    export default function () {}
     `
 
 	client := &http.Client{
@@ -86,6 +90,8 @@ func TestJSLibHTTPPostForm(t *testing.T) {
     export const status = res.status;
     export const error = res.error;
     export const headers = res.headers;
+
+    export default function () {}
     `
 
 	client := &http.Client{
@@ -134,6 +140,8 @@ func TestJSLibHTTPPostJSON(t *testing.T) {
     export const status = res.status;
     export const error = res.error;
     export const headers = res.headers;
+
+    export default function () {}
     `
 
 	client := &http.Client{
diff --git a/js_test.go b/js_test.go
index acefa38..c684319 100644
--- a/js_test.go
+++ b/js_test.go
@@ -94,6 +94,21 @@ func TestJSScrapeNull(t *testing.T) {
 	require.Nil(t, result)
 }
 
+func TestJSScrapeUndefined(t *testing.T) {
+	js := `
+    export default function() { }
+    `
+	exports, err := flyscrape.Compile(js, nil)
+	require.NoError(t, err)
+
+	result, err := exports.Scrape(flyscrape.ScrapeParams{
+		HTML: html,
+		URL:  "http://localhost/",
+	})
+	require.NoError(t, err)
+	require.Nil(t, result)
+}
+
 func TestJSScrapeString(t *testing.T) {
 	js := `
     export default function() {
@@ -131,9 +146,26 @@ func TestJSScrapeArray(t *testing.T) {
 
 	m, ok := result.([]any)
 	require.True(t, ok)
-	require.Equal(t, int64(1), m[0])
-	require.Equal(t, int64(2), m[1])
-	require.Equal(t, int64(3), m[2])
+	require.Equal(t, float64(1), m[0])
+	require.Equal(t, float64(2), m[1])
+	require.Equal(t, float64(3), m[2])
+}
+
+func TestJSScrapeNaN(t *testing.T) {
+	js := `
+    export default function() {
+        return NaN
+    }
+    `
+	exports, err := flyscrape.Compile(js, nil)
+	require.NoError(t, err)
+
+	result, err := exports.Scrape(flyscrape.ScrapeParams{
+		HTML: html,
+		URL:  "http://localhost/",
+	})
+	require.NoError(t, err)
+	require.Nil(t, result)
 }
 
 func TestJSCompileError(t *testing.T) {
diff --git a/modules/jsonprint/jsonprint.go b/modules/jsonprint/jsonprint.go
index a4be5c9..c40a8b9 100644
--- a/modules/jsonprint/jsonprint.go
+++ b/modules/jsonprint/jsonprint.go
@@ -41,9 +41,11 @@ func (m *Module) ReceiveResponse(resp *flyscrape.Response) {
 	o := output{
 		URL:       resp.Request.URL,
 		Data:      resp.Data,
-		Error:     resp.Error,
 		Timestamp: time.Now(),
 	}
+	if resp.Error != nil {
+		o.Error = resp.Error.Error()
+	}
 
 	fmt.Print(flyscrape.Prettify(o, "  "))
 }
@@ -57,7 +59,7 @@ func (m *Module) Finalize() {
 type output struct {
 	URL       string    `json:"url,omitempty"`
 	Data      any       `json:"data,omitempty"`
-	Error     error     `json:"error,omitempty"`
+	Error     string    `json:"error,omitempty"`
 	Timestamp time.Time `json:"timestamp,omitempty"`
 }