From 2a16800305a075ff76ea3a6c9b9ce6d4c5fdcd48 Mon Sep 17 00:00:00 2001
From: aleclarson <alec.stanford.larson@gmail.com>
Date: Wed, 12 Jul 2017 15:28:59 -0400
Subject: [PATCH 1/2] Iterate keys of object when used with `for...in` loop

---
 tags/for.js | 21 +++++++++++++++++++--
 1 file changed, 19 insertions(+), 2 deletions(-)

diff --git a/tags/for.js b/tags/for.js
index de94a7207..a16350718 100644
--- a/tags/for.js
+++ b/tags/for.js
@@ -38,8 +38,10 @@ module.exports = function (liquid) {
     render: function (scope, hash) {
       var collection = Liquid.evalExp(this.collection, scope)
 
-      if (!Array.isArray(collection) ||
-                (Array.isArray(collection) && collection.length === 0)) {
+      if (isObject(collection)) {
+        collection = Object.keys(collection)
+      }
+      if (isEmpty(collection)) {
         return liquid.renderer.renderTemplates(this.elseTemplates, scope)
       }
 
@@ -90,3 +92,18 @@ module.exports = function (liquid) {
     }
   })
 }
+
+function isObject(collection) {
+  if (collection) {
+    const ctr = collection.constructor
+    return ctr === Object || ctr == null
+  }
+  return false
+}
+
+function isEmpty(collection) {
+  if (Array.isArray(collection)) {
+    return !collection.length
+  }
+  return true
+}

From fb52c864b1b87617e15aa6493f9d7a68771003d1 Mon Sep 17 00:00:00 2001
From: aleclarson <alec.stanford.larson@gmail.com>
Date: Thu, 13 Jul 2017 10:27:22 -0400
Subject: [PATCH 2/2] Add `isPlainObject` to 'util/underscore.js'

---
 src/util/underscore.js | 10 ++++++++++
 tags/for.js            | 20 +++-----------------
 2 files changed, 13 insertions(+), 17 deletions(-)

diff --git a/src/util/underscore.js b/src/util/underscore.js
index 85f9b54fb..f3c9a442b 100644
--- a/src/util/underscore.js
+++ b/src/util/underscore.js
@@ -94,6 +94,15 @@ function isObject (value) {
   return value !== null && typeof value === 'object'
 }
 
+/*
+ * Checks if value's prototype is Object or undefined.
+ * @param {any} value The value to check.
+ * @return {Boolean} Returns true if value is a plain object, else false.
+ */
+function isPlainObject(value) {
+  return value && !value.constructor || value.constructor === Object
+}
+
 /*
  * A function to create flexibly-numbered lists of integers,
  * handy for each and map loops. start, if omitted, defaults to 0; step defaults to 1.
@@ -119,6 +128,7 @@ function range (start, stop, step) {
 exports.isString = isString
 exports.isArray = isArray
 exports.isObject = isObject
+exports.isPlainObject = isPlainObject
 exports.isError = isError
 
 exports.range = range
diff --git a/tags/for.js b/tags/for.js
index a16350718..fcc8b11b3 100644
--- a/tags/for.js
+++ b/tags/for.js
@@ -1,6 +1,7 @@
 const Liquid = require('..')
 const lexical = Liquid.lexical
 const mapSeries = require('../src/util/promise.js').mapSeries
+const isPlainObject = require('../src/util/underscore.js').isPlainObject
 const RenderBreakError = Liquid.Types.RenderBreakError
 const assert = require('../src/util/assert.js')
 const re = new RegExp(`^(${lexical.identifier.source})\\s+in\\s+` +
@@ -38,10 +39,10 @@ module.exports = function (liquid) {
     render: function (scope, hash) {
       var collection = Liquid.evalExp(this.collection, scope)
 
-      if (isObject(collection)) {
+      if (isPlainObject(collection)) {
         collection = Object.keys(collection)
       }
-      if (isEmpty(collection)) {
+      if (!Array.isArray(collection) || !collection.length) {
         return liquid.renderer.renderTemplates(this.elseTemplates, scope)
       }
 
@@ -92,18 +93,3 @@ module.exports = function (liquid) {
     }
   })
 }
-
-function isObject(collection) {
-  if (collection) {
-    const ctr = collection.constructor
-    return ctr === Object || ctr == null
-  }
-  return false
-}
-
-function isEmpty(collection) {
-  if (Array.isArray(collection)) {
-    return !collection.length
-  }
-  return true
-}