diff --git a/.eslintrc.espruino.js b/.eslintrc.espruino.js
index 6e44ac98..28db8afd 100644
--- a/.eslintrc.espruino.js
+++ b/.eslintrc.espruino.js
@@ -9,16 +9,22 @@ module.exports = {
   ],
 
   rules: {
-    'no-underscore-dangle': 'off',
-    'func-names': 'off',
-    'space-before-function-paren': ['error', 'never'],
     'comma-dangle': ['error', 'never'],
+    'func-names': 'off',
+    'no-param-reassign': ["error", { "props": false }],
+    'no-underscore-dangle': 'off',
     'object-shorthand': ['error', 'never'],
     'prefer-arrow-callback': 'off',
+    'space-before-function-paren': ['error', 'never'],
   },
 
   globals: {
+    Pin: true,
     analogRead: true,
+    analogWrite: true,
+    digitalRead: true,
+    digitalWrite: true,
+    setWatch: true,
   },
 };
 
diff --git a/nodes/espruino/button.js b/nodes/espruino/button.js
index 2637ee14..5ad376f1 100644
--- a/nodes/espruino/button.js
+++ b/nodes/espruino/button.js
@@ -1,6 +1,6 @@
 
 module.exports.setup = function(e) {
-  var pin = new Pin(e.props.pin);
+  const pin = new Pin(e.props.pin);
 
   setWatch(function(evt) {
     e.fire({ state: evt.state });
diff --git a/nodes/espruino/led.js b/nodes/espruino/led.js
index a0c56bd6..68e395a5 100644
--- a/nodes/espruino/led.js
+++ b/nodes/espruino/led.js
@@ -4,7 +4,11 @@ module.exports.setup = function(e) {
 };
 
 module.exports.evaluate = function(e) {
-  var b = e.inputs.brightness;
-  b = b * b * b;
-  analogWrite(e.context.pin, b);
+  const b = e.inputs.brightness;
+
+  // Adjust duty cycle as a power function to align brightness
+  // perception by human eye
+  const duty = b * b * b;
+
+  analogWrite(e.context.pin, duty);
 };
diff --git a/nodes/espruino/pot.js b/nodes/espruino/pot.js
index 52b22fc9..87aaf8ad 100644
--- a/nodes/espruino/pot.js
+++ b/nodes/espruino/pot.js
@@ -5,5 +5,4 @@ module.exports.setup = function(e) {
 
 module.exports.evaluate = function(e) {
   e.fire({ value: analogRead(e.context.pin) });
-  return analogRead(pin);
 };
diff --git a/nodes/espruino/servo.js b/nodes/espruino/servo.js
index f3f365e5..bd336769 100644
--- a/nodes/espruino/servo.js
+++ b/nodes/espruino/servo.js
@@ -4,8 +4,8 @@ module.exports.setup = function(e) {
 };
 
 module.exports.evaluate = function(e) {
-  var minPulse = +e.props.minPulse;
-  var maxPulse = +e.props.maxPulse;
-  var us = minPulse + (maxPulse - minPulse) * e.inputs.value;
+  const minPulse = +e.props.minPulse;
+  const maxPulse = +e.props.maxPulse;
+  const us = minPulse + (maxPulse - minPulse) * e.inputs.value;
   analogWrite(e.context.pin, us / 20000, { freq: 50 });
 };
diff --git a/nodes/js/constBool.js b/nodes/js/constBool.js
index c7ae2c07..2fd6e640 100644
--- a/nodes/js/constBool.js
+++ b/nodes/js/constBool.js
@@ -1,4 +1,4 @@
 
 module.exports.setup = function(e) {
-  e.fire({value: e.props.value});
+  e.fire({ value: e.props.value });
 };
diff --git a/nodes/js/constNumber.js b/nodes/js/constNumber.js
index c7ae2c07..2fd6e640 100644
--- a/nodes/js/constNumber.js
+++ b/nodes/js/constNumber.js
@@ -1,4 +1,4 @@
 
 module.exports.setup = function(e) {
-  e.fire({value: e.props.value});
+  e.fire({ value: e.props.value });
 };
diff --git a/nodes/js/constSting.js b/nodes/js/constSting.js
index c7ae2c07..2fd6e640 100644
--- a/nodes/js/constSting.js
+++ b/nodes/js/constSting.js
@@ -1,4 +1,4 @@
 
 module.exports.setup = function(e) {
-  e.fire({value: e.props.value});
+  e.fire({ value: e.props.value });
 };
diff --git a/nodes/js/either.js b/nodes/js/either.js
index cbb8052d..bc79add5 100644
--- a/nodes/js/either.js
+++ b/nodes/js/either.js
@@ -1,5 +1,5 @@
 
 module.exports.evaluate = function(e) {
-  var out = e.inputs.inp ? e.inputs.trueValue : e.inputs.falseValue;
+  const out = e.inputs.inp ? e.inputs.trueValue : e.inputs.falseValue;
   return { out: out };
 };
diff --git a/nodes/js/latch.js b/nodes/js/latch.js
index 7fb849e6..4966fe1f 100644
--- a/nodes/js/latch.js
+++ b/nodes/js/latch.js
@@ -4,13 +4,17 @@ module.exports.setup = function(e) {
 };
 
 module.exports.evaluate = function(e) {
-  var inputs = e.inputs;
-  var ctx = e.context;
+  const inputs = e.inputs;
+  let newState;
+
   if (inputs.toggle) {
-    return (ctx.state = !ctx.state);
+    newState = !e.context.state;
   } else if (inputs.set) {
-    return (ctx.state = true);
+    newState = true;
   } else /* if (inputs.reset) */ {
-    return (ctx.state = false);
+    newState = false;
   }
+
+  e.context.state = newState;
+  return { state: newState };
 };
diff --git a/nodes/js/map.js b/nodes/js/map.js
index 2a71a2f0..82b83c86 100644
--- a/nodes/js/map.js
+++ b/nodes/js/map.js
@@ -1,8 +1,9 @@
 
 module.exports.evaluate = function(e) {
-  var inputs = e.inputs;
-  var k = (inputs.inp - inputs.inA) / (inputs.inB - inputs.inA);
-  var out = inputs.outA + k * (inputs.outB - inputs.outA);
+  const inputs = e.inputs;
+  const k = (inputs.inp - inputs.inA) / (inputs.inB - inputs.inA);
+
+  let out = inputs.outA + k * (inputs.outB - inputs.outA);
 
   if (inputs.clip) {
     if (inputs.outB > inputs.outA) {
diff --git a/nodes/js/not.js b/nodes/js/not.js
index f6cf6191..50aaf45b 100644
--- a/nodes/js/not.js
+++ b/nodes/js/not.js
@@ -1,4 +1,4 @@
 
 module.exports.evaluate = function(e) {
-  return {out: !e.inputs.in};
+  return { out: !e.inputs.in };
 };
diff --git a/package.json b/package.json
index 6e4e4ed5..f16f15dc 100644
--- a/package.json
+++ b/package.json
@@ -8,7 +8,7 @@
     "build-chrome": "webpack --progress --colors --config webpack/chrome-dev.js",
     "dev-chrome": "webpack --watch --progress --colors --config webpack/chrome-dev.js",
     "lint-es6": "eslint --ext .js --ext .jsx ./app ./targets ./test --ignore-path targets/xod-espruino/runtime.js || true",
-    "lint-espruino": "eslint --config .eslintrc.espruino.js targets/xod-espruino/runtime.js || true",
+    "lint-espruino": "eslint --config .eslintrc.espruino.js targets/xod-espruino/runtime.js nodes/js nodes/espruino || true",
     "lint": "npm-run-all lint-es6 lint-espruino",
     "test": "mocha-webpack \"test/**/*Spec.js\"",
     "travis": "npm-run-all --continue-on-error lint test"