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

session/script_builtin.go

@@ -0,0 +1,33 @@
+package session
+
+import (
+	"github.com/bettercap/bettercap/js"
+	"github.com/robertkrimen/otto"
+)
+
+func jsEnvFunc(call otto.FunctionCall) otto.Value {
+	argv := call.ArgumentList
+	argc := len(argv)
+
+	if argc == 1 {
+		// get
+		varName := call.Argument(0).String()
+		if found, varValue := I.Env.Get(varName); found {
+			v, err := otto.ToValue(varValue)
+			if err != nil {
+				return js.ReportError("could not convert to string: %s", varValue)
+			}
+			return v
+		}
+
+	} else if argc == 2 {
+		// set
+		varName := call.Argument(0).String()
+		varValue := call.Argument(1).String()
+		I.Env.Set(varName, varValue)
+	} else {
+		return js.ReportError("env: expected 1 or 2 arguments, %d given instead.", argc)
+	}
+	return js.NullValue
+}
+