new: new -script allows to run JS code to instrument session

js/data.go

@@ -0,0 +1,86 @@
+package js
+
+import (
+	"bytes"
+	"compress/gzip"
+	"encoding/base64"
+	"github.com/robertkrimen/otto"
+)
+
+func btoa(call otto.FunctionCall) otto.Value {
+	varValue := base64.StdEncoding.EncodeToString([]byte(call.Argument(0).String()))
+	v, err := otto.ToValue(varValue)
+	if err != nil {
+		return ReportError("Could not convert to string: %s", varValue)
+	}
+	return v
+}
+
+func atob(call otto.FunctionCall) otto.Value {
+	varValue, err := base64.StdEncoding.DecodeString(call.Argument(0).String())
+	if err != nil {
+		return ReportError("Could not decode string: %s", call.Argument(0).String())
+	}
+	v, err := otto.ToValue(string(varValue))
+	if err != nil {
+		return ReportError("Could not convert to string: %s", varValue)
+	}
+	return v
+}
+
+func gzipCompress(call otto.FunctionCall) otto.Value {
+	argv := call.ArgumentList
+	argc := len(argv)
+	if argc != 1 {
+		return ReportError("gzipCompress: expected 1 argument, %d given instead.", argc)
+	}
+
+	uncompressedBytes := []byte(argv[0].String())
+
+	var writerBuffer bytes.Buffer
+	gzipWriter := gzip.NewWriter(&writerBuffer)
+	_, err := gzipWriter.Write(uncompressedBytes)
+	if err != nil {
+		return ReportError("gzipCompress: could not compress data: %s", err.Error())
+	}
+	gzipWriter.Close()
+
+	compressedBytes := writerBuffer.Bytes()
+
+	v, err := otto.ToValue(string(compressedBytes))
+	if err != nil {
+		return ReportError("Could not convert to string: %s", err.Error())
+	}
+
+	return v
+}
+
+func gzipDecompress(call otto.FunctionCall) otto.Value {
+	argv := call.ArgumentList
+	argc := len(argv)
+	if argc != 1 {
+		return ReportError("gzipDecompress: expected 1 argument, %d given instead.", argc)
+	}
+
+	compressedBytes := []byte(argv[0].String())
+	readerBuffer := bytes.NewBuffer(compressedBytes)
+
+	gzipReader, err := gzip.NewReader(readerBuffer)
+	if err != nil {
+		return ReportError("gzipDecompress: could not create gzip reader: %s", err.Error())
+	}
+
+	var decompressedBuffer bytes.Buffer
+	_, err = decompressedBuffer.ReadFrom(gzipReader)
+	if err != nil {
+		return ReportError("gzipDecompress: could not decompress data: %s", err.Error())
+	}
+
+	decompressedBytes := decompressedBuffer.Bytes()
+	v, err := otto.ToValue(string(decompressedBytes))
+	if err != nil {
+		return ReportError("Could not convert to string: %s", err.Error())
+	}
+
+	return v
+}