diff --git a/internal/complete/complete.go b/internal/complete/complete.go
index 2e6e128..abab15d 100644
--- a/internal/complete/complete.go
+++ b/internal/complete/complete.go
@@ -53,6 +53,7 @@ var globals = []string{
 	"keys",
 	"values",
 	"skip",
+	"list",
 }
 
 //go:embed prelude.js
diff --git a/internal/engine/engine.go b/internal/engine/engine.go
index 60e4b2f..86b338d 100644
--- a/internal/engine/engine.go
+++ b/internal/engine/engine.go
@@ -91,7 +91,7 @@ func Reduce(args []string) {
 	for _, fn := range fns {
 		code.WriteString(Transform(fn))
 	}
-	code.WriteString("JSON.stringify(json)")
+	code.WriteString(`json === skip ? '__skip__' : JSON.stringify(json)`)
 
 	vm := goja.New()
 	vm.Set("println", func(s string) any {
@@ -111,6 +111,10 @@ func Reduce(args []string) {
 		return
 	}
 
+	if output == "__skip__" {
+		return
+	}
+
 	node, err := jsonx.Parse([]byte(output))
 	if err != nil {
 		println(err.Error())
diff --git a/internal/engine/prelude.js b/internal/engine/prelude.js
index b1fb47e..60c3cb9 100644
--- a/internal/engine/prelude.js
+++ b/internal/engine/prelude.js
@@ -2,7 +2,13 @@ const console = {
   log: function (...args) {
     const parts = []
     for (const arg of args) {
-      parts.push(typeof arg === 'string' ? arg : JSON.stringify(arg, null, 2))
+      if (typeof arg === 'undefined') {
+        parts.push('undefined')
+      } else if (typeof arg === 'string') {
+        parts.push(arg)
+      } else {
+        parts.push(JSON.stringify(arg, null, 2))
+      }
     }
     println(parts.join(' '))
   },
diff --git a/internal/engine/stdlib.js b/internal/engine/stdlib.js
index 1a95e0e..0d537bc 100644
--- a/internal/engine/stdlib.js
+++ b/internal/engine/stdlib.js
@@ -1,3 +1,5 @@
+const skip = Symbol('skip')
+
 function apply(fn, ...args) {
   if (typeof fn === 'function') return fn(...args)
   return fn
@@ -89,3 +91,11 @@ function values(x) {
   if (typeof x === 'object' && x !== null) return Object.values(x)
   throw new Error(`Cannot get values of ${typeof x}`)
 }
+
+function list(x) {
+  if (Array.isArray(x)) {
+    for (const y of x) console.log(y)
+    return skip
+  }
+  throw new Error(`Cannot list ${typeof x}`)
+}
diff --git a/npm/index.js b/npm/index.js
index 6543114..76e0b60 100644
--- a/npm/index.js
+++ b/npm/index.js
@@ -233,6 +233,14 @@ async function run(json, code) {
     if (typeof x === 'object' && x !== null) return Object.values(x)
     throw new Error(`Cannot get values of ${typeof x}`)
   }
+
+  function list(x) {
+    if (Array.isArray(x)) {
+      for (const y of x) console.log(y)
+      return skip
+    }
+    throw new Error(`Cannot list ${typeof x}`)
+  }
 }
 
 async function read(fd = 0) {
diff --git a/reduce.go b/reduce.go
index 0a5b4d2..1e33a2b 100644
--- a/reduce.go
+++ b/reduce.go
@@ -14,8 +14,12 @@ import (
 var src []byte
 
 func reduce(fns []string) {
-	var deno bool
+	if _, ok := os.LookupEnv("FX_JS"); ok {
+		engine.Reduce(fns)
+		return
+	}
 
+	var deno bool
 	bin, err := exec.LookPath("node")
 	if err != nil {
 		bin, err = exec.LookPath("deno")
diff --git a/version.go b/version.go
index 5b3a023..07d0e77 100644
--- a/version.go
+++ b/version.go
@@ -1,3 +1,3 @@
 package main
 
-const version = "33.0.0"
+const version = "34.0.0"