From ff5d1c3b224534d75822caf92060fc4127732c2f Mon Sep 17 00:00:00 2001
From: Gareth Daniel Smith <garethdanielsmith@gmail.com>
Date: Sun, 29 Jul 2018 14:55:58 +0100
Subject: [PATCH] Deal with the case where the first element does not have the
 requested attribute: return Nothing rather than undefined.

---
 src/Cheerio.js         | 8 +++++++-
 src/Cheerio.purs       | 3 ++-
 test/Test/Cheerio.purs | 4 ++++
 3 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/src/Cheerio.js b/src/Cheerio.js
index 73ec97e..cc32335 100644
--- a/src/Cheerio.js
+++ b/src/Cheerio.js
@@ -2,7 +2,13 @@ const cheerio = require('cheerio')
 
 // Attributes
 exports.attrImpl = function(nothing, just, name, cheerioInst) {
-  return cheerioInst.length ? just(cheerioInst.attr(name)) : nothing;
+
+  if (cheerioInst.length > 0) {
+    const value = cheerioInst.attr(name);
+    return value != null ? just(value) : nothing;
+  }
+
+  return nothing;
 }
 
 exports.hasClassImpl = function(className, cheerioInst) {
diff --git a/src/Cheerio.purs b/src/Cheerio.purs
index 888ab8c..4386ddb 100644
--- a/src/Cheerio.purs
+++ b/src/Cheerio.purs
@@ -10,7 +10,8 @@ foreign import attrImpl :: forall a.
   Fn4 (Maybe a) (a -> Maybe a) String Cheerio (Maybe String)
 
 -- | Gets an attribute value from the first selected element, returning
--- | Nothing when there are no selected elements.
+-- | Nothing when there are no selected elements, or when the first selected
+-- | element does not have the specified attribute.
 attr :: String -> Cheerio -> Maybe String
 attr = runFn4 attrImpl Nothing Just
 
diff --git a/test/Test/Cheerio.purs b/test/Test/Cheerio.purs
index c4d0e30..fdd6eb3 100644
--- a/test/Test/Cheerio.purs
+++ b/test/Test/Cheerio.purs
@@ -44,6 +44,10 @@ suites = do
         (Just "fruits")
         (loadRoot htmlEx # find "ul" # attr "id")
 
+      Assert.equal
+        Nothing
+        (loadRoot htmlEx # find "ul" # attr "no-such-attribute")
+
       Assert.equal
         Nothing
         (emptyCheerio # attr "id")