From b59952e12e2f0fe1782d894fd4a6edb2f2327a43 Mon Sep 17 00:00:00 2001
From: "ZUO, JACOB [ITUIS]" <zuo@iastate.edu>
Date: Thu, 9 Jan 2020 13:28:22 -0600
Subject: [PATCH 1/3] fixing exceptions when attribute contains no value

---
 src/htmlminifier.js | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/htmlminifier.js b/src/htmlminifier.js
index d7efa991..6aac94f2 100644
--- a/src/htmlminifier.js
+++ b/src/htmlminifier.js
@@ -182,7 +182,12 @@ function isExecutableScript(tag, attrs) {
 }
 
 function isStyleLinkTypeAttribute(attrValue) {
-  attrValue = trimWhitespace(attrValue).toLowerCase();
+  attrValue = trimWhitespace(attrValue);
+  if (!attrValue) {
+    return true;
+  }
+  
+  attrValue = attrValue.toLowerCase();
   return attrValue === '' || attrValue === 'text/css';
 }
 

From c9497088d7f537d41acb6ad7097536695a34fd7f Mon Sep 17 00:00:00 2001
From: "ZUO, JACOB [ITUIS]" <zuo@iastate.edu>
Date: Thu, 9 Jan 2020 13:36:22 -0600
Subject: [PATCH 2/3] handling other illegal entries as well

---
 src/htmlminifier.js | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/src/htmlminifier.js b/src/htmlminifier.js
index 6aac94f2..89d279a8 100644
--- a/src/htmlminifier.js
+++ b/src/htmlminifier.js
@@ -183,11 +183,13 @@ function isExecutableScript(tag, attrs) {
 
 function isStyleLinkTypeAttribute(attrValue) {
   attrValue = trimWhitespace(attrValue);
-  if (!attrValue) {
-    return true;
+
+  if (typeof attrValue !== 'string') {
+    attrValue = '';
+  } else {
+    attrValue = attrValue.toLowerCase();
   }
   
-  attrValue = attrValue.toLowerCase();
   return attrValue === '' || attrValue === 'text/css';
 }
 

From eaacd0e1f60b130998e323db672ba22fbacc3914 Mon Sep 17 00:00:00 2001
From: Jacob Zuo <chopinsky@live.com>
Date: Mon, 3 Feb 2020 16:04:13 -0600
Subject: [PATCH 3/3] only handle exceptions with 'undefined' values

reverting from a more sweeping change where any attrValue not of the type of 'string' is treated as a blank entry.
---
 src/htmlminifier.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/htmlminifier.js b/src/htmlminifier.js
index 89d279a8..c4d373bd 100644
--- a/src/htmlminifier.js
+++ b/src/htmlminifier.js
@@ -184,7 +184,7 @@ function isExecutableScript(tag, attrs) {
 function isStyleLinkTypeAttribute(attrValue) {
   attrValue = trimWhitespace(attrValue);
 
-  if (typeof attrValue !== 'string') {
+  if (typeof attrValue === 'undefined') {
     attrValue = '';
   } else {
     attrValue = attrValue.toLowerCase();