From 412fbf8976f93b8622314c7351c072c8ca0dd681 Mon Sep 17 00:00:00 2001
From: Michael Best <mbest@dasya.com>
Date: Fri, 15 Mar 2013 16:02:42 -1000
Subject: [PATCH] Use strict equality when determining whether to update the
 value binding.

---
 spec/defaultBindings/valueBehaviors.js | 9 +++++++++
 src/binding/defaultBindings/value.js   | 7 +------
 2 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/spec/defaultBindings/valueBehaviors.js b/spec/defaultBindings/valueBehaviors.js
index 0206faf66..2dc9805cc 100644
--- a/spec/defaultBindings/valueBehaviors.js
+++ b/spec/defaultBindings/valueBehaviors.js
@@ -34,6 +34,15 @@ describe('Binding: Value', function() {
         expect(testNode.childNodes[0].value).toEqual("456");
     });
 
+    it('For observable values, should update on change if new value is \'strictly\' different from previous value', function() {
+        var myobservable = new ko.observable("+123");
+        testNode.innerHTML = "<input data-bind='value:someProp' />";
+        ko.applyBindings({ someProp: myobservable }, testNode);
+        expect(testNode.childNodes[0].value).toEqual("+123");
+        myobservable(123);
+        expect(testNode.childNodes[0].value).toEqual("123");
+    });
+
     it('For writeable observable values, should catch the node\'s onchange and write values back to the observable', function () {
         var myobservable = new ko.observable(123);
         testNode.innerHTML = "<input data-bind='value:someProp' />";
diff --git a/src/binding/defaultBindings/value.js b/src/binding/defaultBindings/value.js
index a4febb7bc..b7e2ce687 100755
--- a/src/binding/defaultBindings/value.js
+++ b/src/binding/defaultBindings/value.js
@@ -47,12 +47,7 @@ ko.bindingHandlers['value'] = {
         var valueIsSelectOption = ko.utils.tagNameLower(element) === "select";
         var newValue = ko.utils.unwrapObservable(valueAccessor());
         var elementValue = ko.selectExtensions.readValue(element);
-        var valueHasChanged = (newValue != elementValue);
-
-        // JavaScript's 0 == "" behavious is unfortunate here as it prevents writing 0 to an empty text box (loose equality suggests the values are the same).
-        // We don't want to do a strict equality comparison as that is more confusing for developers in certain cases, so we specifically special case 0 != "" here.
-        if ((newValue === 0) && (elementValue !== 0) && (elementValue !== "0"))
-            valueHasChanged = true;
+        var valueHasChanged = (newValue !== elementValue);
 
         if (valueHasChanged) {
             var applyValueAction = function () { ko.selectExtensions.writeValue(element, newValue); };