From 6fa7980cfefb019087235ac870daf13f87b69270 Mon Sep 17 00:00:00 2001
From: Matthew Dean <matthew-dean@users.noreply.github.com>
Date: Tue, 3 Jul 2018 19:38:31 -0700
Subject: [PATCH] Fixes #3182

---
 lib/less/tree/javascript.js | 5 +++--
 test/css/javascript.css     | 1 +
 test/less/javascript.less   | 1 +
 3 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/lib/less/tree/javascript.js b/lib/less/tree/javascript.js
index cdafcae8b..9e77e797d 100644
--- a/lib/less/tree/javascript.js
+++ b/lib/less/tree/javascript.js
@@ -13,10 +13,11 @@ JavaScript.prototype = new JsEvalNode();
 JavaScript.prototype.type = 'JavaScript';
 JavaScript.prototype.eval = function(context) {
     var result = this.evaluateJavaScript(this.expression, context);
+    var type = typeof result;
 
-    if (typeof result === 'number') {
+    if (type === 'number' && !isNaN(result)) {
         return new Dimension(result);
-    } else if (typeof result === 'string') {
+    } else if (type === 'string') {
         return new Quoted('"' + result + '"', result, this.escaped, this._index);
     } else if (Array.isArray(result)) {
         return new Anonymous(result.join(', '));
diff --git a/test/css/javascript.css b/test/css/javascript.css
index 9cc1c3e91..9e33ac777 100644
--- a/test/css/javascript.css
+++ b/test/css/javascript.css
@@ -8,6 +8,7 @@
   multiline: 2;
 }
 .scope {
+  empty: ;
   var: 42;
   escaped: 7px;
 }
diff --git a/test/less/javascript.less b/test/less/javascript.less
index a8e7eb37f..505090cdb 100644
--- a/test/less/javascript.less
+++ b/test/less/javascript.less
@@ -9,6 +9,7 @@
            return x})()`;
 }
 .scope {
+    empty: `+function(){}`;
     @foo: 42;
     var: `parseInt(this.foo.toJS())`;
     escaped: ~`2 + 5 + 'px'`;