diff --git a/lib/DataStore/DataStore.js b/lib/DataStore/DataStore.js
index ee417f7..f9f6ee3 100644
--- a/lib/DataStore/DataStore.js
+++ b/lib/DataStore/DataStore.js
@@ -56,6 +56,7 @@ class DataStore {
 
     fillReferencesValuesFromEntry(entry, referencedValues, fillSimpleReference) {
         for (let referenceField in referencedValues) {
+            if (!referencedValues.hasOwnProperty(referenceField)) continue;
             let reference = referencedValues[referenceField],
                 choices = this.getReferenceChoicesById(reference),
                 entries = [],
@@ -63,6 +64,7 @@ class DataStore {
 
             if (reference.type() === 'reference_many') {
                 for (let i in identifier) {
+                    if (!identifier.hasOwnProperty(i)) continue;
                     let id = identifier[i];
                     entries.push(choices[id]);
                 }
diff --git a/lib/Field/Field.js b/lib/Field/Field.js
index a1db9d0..e6e7693 100644
--- a/lib/Field/Field.js
+++ b/lib/Field/Field.js
@@ -99,6 +99,7 @@ class Field {
 
     getMappedValue(value, entry) {
         for (let i in this._maps) {
+            if (!this._maps.hasOwnProperty(i)) continue;
             value = this._maps[i](value, entry);
         }
 
@@ -126,6 +127,7 @@ class Field {
 
     getTransformedValue(value, entry) {
         for (let i in this._transforms) {
+            if (!this._transforms.hasOwnProperty(i)) continue;
             value = this._transforms[i](value, entry);
         }
 
diff --git a/lib/Field/ReferenceField.js b/lib/Field/ReferenceField.js
index 43d3ed9..ca82b08 100644
--- a/lib/Field/ReferenceField.js
+++ b/lib/Field/ReferenceField.js
@@ -115,6 +115,7 @@ class ReferenceField extends Field {
 
             if (identifier instanceof Array) {
                 for (let j in identifier) {
+                    if (!identifier.hasOwnProperty(j)) continue;
                     results[identifier[j]] = true;
                 }
                 continue;
diff --git a/lib/Queries/ReadQueries.js b/lib/Queries/ReadQueries.js
index aa9776d..8d8522e 100644
--- a/lib/Queries/ReadQueries.js
+++ b/lib/Queries/ReadQueries.js
@@ -125,9 +125,11 @@ class ReadQueries extends Queries {
                 let data = {};
                 let name;
                 for (name in results[0]) {
+                    if (!results[0].hasOwnProperty(name)) continue;
                     data[name] = results[0][name];
                 }
                 for (name in results[1]) {
+                    if (!results[1].hasOwnProperty(name)) continue;
                     data[name] = results[1][name];
                 }
                 return data;
@@ -152,11 +154,13 @@ class ReadQueries extends Queries {
             calls = [];
 
         for (let i in references) {
+            if (!references.hasOwnProperty(i)) continue;
             let reference = references[i],
                 targetEntity = reference.targetEntity(),
                 identifiers = reference.getIdentifierValues(rawValues);
 
             for (let k in identifiers) {
+                if (!identifiers.hasOwnProperty(k)) continue;
                 calls.push(getOne(targetEntity, 'listView', identifiers[k], reference.name()));
             }
         }
@@ -182,6 +186,7 @@ class ReadQueries extends Queries {
             calls = [];
 
         for (let i in references) {
+            if (!references.hasOwnProperty(i)) continue;
             let reference = references[i],
                 targetEntity = reference.targetEntity(),
                 identifiers = reference.getIdentifierValues(rawValues);
@@ -211,6 +216,7 @@ class ReadQueries extends Queries {
             getRawValues = this.getRawValues.bind(this);
 
         for (let i in references) {
+            if (!references.hasOwnProperty(i)) continue;
             let reference = references[i];
             let targetEntity = reference.targetEntity();
 
@@ -274,6 +280,7 @@ class ReadQueries extends Queries {
                     i = 0;
 
                 for (let j in references) {
+                    if (!references.hasOwnProperty(j)) continue;
                     let reference = references[j],
                         response = responses[i++];
 
@@ -310,11 +317,12 @@ class ReadQueries extends Queries {
                     i = 0;
 
                 for (let j in references) {
+                    if (!references.hasOwnProperty(j)) continue;
                     let data = [],
                         reference = references[j],
                         identifiers = reference.getIdentifierValues(rawValues);
 
-                    for (let k in identifiers) {
+                    for (let k of identifiers) {
                         response = responses[i++];
                         if (response.status == 'error') {
                             // one of the responses failed
@@ -349,6 +357,7 @@ class ReadQueries extends Queries {
             calls = [];
 
         for (let i in referencedLists) {
+            if (!referencedLists.hasOwnProperty(i)) continue;
             let referencedList = referencedLists[i],
                 targetEntity = referencedList.targetEntity(),
                 viewName = referencedList.datagridName(),
@@ -376,6 +385,7 @@ class ReadQueries extends Queries {
                     entries = {};
 
                 for (let i in referencedLists) {
+                    if (!referencedLists.hasOwnProperty(i)) continue;
                     let response = responses[j++];
                     if (response.status == 'error') {
                         // If a response fail, skip it
diff --git a/lib/Utils/PromisesResolver.js b/lib/Utils/PromisesResolver.js
index 6edc915..72fd17c 100644
--- a/lib/Utils/PromisesResolver.js
+++ b/lib/Utils/PromisesResolver.js
@@ -28,6 +28,7 @@ class PromisesResolver {
                     states[key] = true;
                     results[key] = result; // result may be an error
                     for (let i in states) {
+                        if (!states.hasOwnProperty(i)) continue;
                         if (!states[i]) {
                             return;
                         }
diff --git a/lib/Utils/orderElement.js b/lib/Utils/orderElement.js
index 6ddced5..5b29ed1 100644
--- a/lib/Utils/orderElement.js
+++ b/lib/Utils/orderElement.js
@@ -4,6 +4,7 @@ export default {
             objectKey;
 
         for (objectKey in input) {
+            if (!input.hasOwnProperty(objectKey)) continue;
             results.push(input[objectKey]);
         }
 
diff --git a/lib/View/View.js b/lib/View/View.js
index 9107952..18bee6a 100644
--- a/lib/View/View.js
+++ b/lib/View/View.js
@@ -140,6 +140,7 @@ class View {
             console.warn('Passing literal of Field to fields method is deprecated use array instead');
             let result = [];
             for (let fieldName in arg) {
+                if (!arg.hasOwnProperty(fieldName)) continue;
                 result = result.concat(View.flatten(arg[fieldName]));
             }
             return result;
diff --git a/tests/before_all.js b/tests/before_all.js
new file mode 100644
index 0000000..a8ab6d5
--- /dev/null
+++ b/tests/before_all.js
@@ -0,0 +1,18 @@
+
+beforeEach(function() {
+    if (!Object.prototype.test_prototype_entry) {
+        Object.prototype.test_prototype_entry =
+            "Don't use for..in to enumerate Object properties, as users are free to " +
+            "add entries to the Object prototype, for example for polyfills. " +
+            "You should instead use\n" +
+            "  for (let i in xs) { if (!xs.hasOwnProperty(i)) continue; var x = xs[i]; ... }";
+    }
+
+    if (!Array.prototype.test_prototype_entry) {
+        Array.prototype.test_prototype_entry =
+            "Don't use for..in to enumerate Array properties, as users are free to " +
+            "add entries to the Array prototype, for example for polyfills. " +
+            "You should instead use\n" +
+            "  for (let i in xs) { if (!xs.hasOwnProperty(i)) continue; var x = xs[i]; ... }";
+    }
+});