diff --git a/.gitignore b/.gitignore
index 0a8eff8..c39891f 100644
--- a/.gitignore
+++ b/.gitignore
@@ -92,3 +92,4 @@ md_pdf/assets/templates/cover.html
 md_pdf/assets/static/style.css
 md_pdf/assets/csl/
 md_pdf/assets/styles-master/
+node_modules/
diff --git a/circle.yml b/circle.yml
index 1e8238b..6ffe8d9 100644
--- a/circle.yml
+++ b/circle.yml
@@ -1,11 +1,14 @@
 machine:
   python:
     version: 3.6.0
+  node:
+    version: 6.10.2
 
 
 dependencies:
   post:
     - pip install -r dev-requirements.txt
+    - npm install
 
 
 test:
@@ -13,3 +16,4 @@ test:
     - flake8 md_pdf/ --ignore=E128,E501
     - safety check
     - bandit -r md_pdf/
+    - npm test
diff --git a/md_pdf/assets/static/context.js b/md_pdf/assets/static/context.js
index bb59599..90adc1b 100644
--- a/md_pdf/assets/static/context.js
+++ b/md_pdf/assets/static/context.js
@@ -1,3 +1,5 @@
+'use strict';
+
 function subst() {
   var vars = {};
   var query_strings_from_url = document.location.search.substring(1).split('&');
@@ -18,3 +20,5 @@ function subst() {
     }
   }
 }
+
+window.subst = subst();
diff --git a/package.json b/package.json
index e914b72..33e2150 100644
--- a/package.json
+++ b/package.json
@@ -4,7 +4,9 @@
   "private": true,
   "description": "",
   "scripts": {
-    "test": "echo \"Error: no test specified\" && exit 1"
+    "test": "npm run lint-scss && npm run lint-js",
+    "lint-scss": "sass-lint -vq md_pdf/assets/static/**/*.scss",
+    "lint-js": "eslint -c eslint-config-dabapps/base/.eslintrc md_pdf/assets/static/**/*.js"
   },
   "repository": {
     "type": "git",
@@ -16,6 +18,7 @@
   },
   "homepage": "https://github.com/RealOrangeOne/md-pdf#readme",
   "devDependencies": {
-    "eslint-config": "dabapps/eslint-config.git#2.0.4"
+    "eslint-config": "dabapps/eslint-config.git#2.0.4",
+    "sass-lint": "1.10.2"
   }
 }