diff --git a/.eslintrc.json b/.eslintrc.json
new file mode 100644
index 0000000..eff21c6
--- /dev/null
+++ b/.eslintrc.json
@@ -0,0 +1,22 @@
+{
+    "parserOptions": {
+      "ecmaVersion": "latest",
+      "sourceType": "module"
+    },
+
+    "env": {
+        "node": true,
+        "browser": true,
+        "es6": true
+    },
+    "rules": {
+      "no-unsafe-finally": "off",
+      "no-unused-vars": "off",
+      "no-use-before-define": [2, { "functions": false ,  "classes": false, "variables": false}],
+      "no-console": "off"
+    },
+    "globals": {
+      "globalThis": true
+    },
+    "extends": "eslint:recommended"
+}
diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 4db4cef..ff6e4c7 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -15,5 +15,6 @@ jobs:
 
       - name: test
         run: |
+          eslint src test
           node test/run.js
           node test/self_hosted_test.js
diff --git a/src/editor/editor.js b/src/editor/editor.js
index e31efbc..b4c0257 100644
--- a/src/editor/editor.js
+++ b/src/editor/editor.js
@@ -80,7 +80,7 @@ export class Editor {
     this.markers = {}
     this.sessions = {}
 
-    this.ace_editor = ace.edit(this.editor_container)
+    this.ace_editor = globalThis.ace.edit(this.editor_container)
 
     this.ace_editor.setOptions({
       behavioursEnabled: false,
@@ -141,7 +141,7 @@ export class Editor {
   ensure_session(file, code) {
     let session = this.sessions[file]
     if(session == null) {
-      session = ace.createEditSession(code)
+      session = globalThis.ace.createEditSession(code)
       this.sessions[file] = session
       session.setUseWorker(false)
       session.setOptions({
@@ -389,7 +389,7 @@ export class Editor {
     const from_pos = session.doc.indexToPosition(from)
     const to_pos = session.doc.indexToPosition(to)
     const markerId = session.addMarker(
-      new ace.Range(from_pos.row,from_pos.column,to_pos.row,to_pos.column), 
+      new globalThis.ace.Range(from_pos.row,from_pos.column,to_pos.row,to_pos.column), 
       className
     )
     if(this.markers[file] == null){
diff --git a/src/editor/value_explorer.js b/src/editor/value_explorer.js
index ba64201..60ecd6d 100644
--- a/src/editor/value_explorer.js
+++ b/src/editor/value_explorer.js
@@ -136,7 +136,6 @@ export const header = object => {
   } else {
     return object.toString()
   }
-  return header
 }
 
 const get_path = (o, path) => {
diff --git a/src/filesystem.js b/src/filesystem.js
index 80707c6..be8e69f 100644
--- a/src/filesystem.js
+++ b/src/filesystem.js
@@ -23,7 +23,7 @@ globalThis.clear_directory_handle = () => {
 let dir_handle
 
 const request_directory_handle = async () => {
-  dir_handle = await showDirectoryPicker()
+  dir_handle = await globalThis.showDirectoryPicker()
   await send_message({type: 'SET', data: dir_handle})
   return dir_handle
 }
diff --git a/src/find_definitions.js b/src/find_definitions.js
index 11714bd..0e3f924 100644
--- a/src/find_definitions.js
+++ b/src/find_definitions.js
@@ -180,7 +180,6 @@ const concat_path = (base, i) => {
   } else {
     return result
   }
-  return result
 }
 
 export const topsort_modules = (modules) => {
diff --git a/src/parse_js.js b/src/parse_js.js
index fa99f9a..265d50a 100644
--- a/src/parse_js.js
+++ b/src/parse_js.js
@@ -83,7 +83,7 @@ const tokenize_js = (str) => {
 
     {name: 'comment'            , re: '//[^\n]*'},
     {name: 'comment'            , re: '\\/\\*[\\s\\S]*?\\*\\/'},
-    {name: 'newline'            , re: '[\r\n\]+'},
+    {name: 'newline'            , re: '[\r\n]+'},
     
 
     // whitespace except newline
@@ -1423,11 +1423,6 @@ const update_children_not_rec = (node, children = node.children) => {
     }
   } else if(node.type == 'call_args') {
     return node
-  } else if(node.type == 'member_access') {
-    return {...node,
-      object: children[0],
-      property: children[1],
-    }
   } else if(node.type == 'spread') {
     return {...node,
       expr: children[0],
diff --git a/src/runtime.js b/src/runtime.js
index 27c8442..6c8168c 100644
--- a/src/runtime.js
+++ b/src/runtime.js
@@ -46,7 +46,6 @@ const do_run = function*(module_fns, cxt, io_cache){
       io_cache_resolver_is_set: false,
       // Map of (index in io_cache) -> resolve
       io_cache_resolvers: new Map(),
-      io_cache_is_replay_aborted: false,
       io_cache_index: 0,
     }