✨ feat: jsonutil - add new util func IsJSON(), IsJSONFast() for check…

… JSON

jsonutil/jsonutil.go

@@ -100,6 +100,35 @@ func Mapping(src, dst any) error {
 	return Decode(bts, dst)
 }
 
+// IsJSON check if the string is valid JSON. (Note: uses json.Unmarshal)
+func IsJSON(s string) bool {
+	if s == "" {
+		return false
+	}
+
+	var js json.RawMessage
+	return json.Unmarshal([]byte(s), &js) == nil
+}
+
+// IsJSONFast simple and fast check input string is valid JSON.
+func IsJSONFast(s string) bool {
+	ln := len(s)
+	if ln < 2 {
+		return false
+	}
+	if ln == 2 {
+		return s == "{}" || s == "[]"
+	}
+
+	// object
+	if s[0] == '{' {
+		return s[ln-1] == '}' && s[1] == '"'
+	}
+
+	// array
+	return s[0] == '[' && s[ln-1] == ']'
+}
+
 // `(?s:` enable match multi line
 var jsonMLComments = regexp.MustCompile(`(?s:/\*.*?\*/\s*)`)
 

jsonutil/jsonutil_test.go

@@ -108,6 +108,32 @@ func TestWriteReadFile(t *testing.T) {
 	assert.Eq(t, 200, user.Age)
 }
 
+func TestIsJsonFast(t *testing.T) {
+	testCases := []struct {
+		name     string
+		input    string
+		expected bool
+	}{
+		{"empty string", "", false},
+		{"single character", "a", false},
+		{"two characters object", "{}", true},
+		{"two characters slice", "[]", true},
+		{"invalid json", "{a}", false},
+		{"valid json object", `{"a": 1}`, true},
+		{"valid json array", `[1]`, true},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			assert.Eq(t, tc.expected, jsonutil.IsJSON(tc.input))
+
+			if jsonutil.IsJSONFast(tc.input) != tc.expected {
+				t.Errorf("expected %v but got %v", tc.expected, !tc.expected)
+			}
+		})
+	}
+}
+
 func TestStripComments(t *testing.T) {
 	is := assert.New(t)