This article has been moved here
http://ronanquillevere.github.io/2012/12/12/javascript-object-comparison.html
-- old version --
Hello everyone,
Today, working on an elegant message box system for our Sencha Touch mobile application I asked myself the following question : How does the === operator works when comparing objects ?
Well I found this article useful : http://javascript.about.com/od/byexample/a/objectoriented-compareobject-example.htm
The fundamental point is, when you assign an object to a var in javascript, this var is on only a reference to the object. The === comparator will compare the object your reference is pointing on. The following code will only display 'true' values.
var ob1, ob2, ob3;
ob1 = {prop1: 'a', prop2: 'b'};
ob2 = {prop1: 'a', prop2: 'b'};
ob3 = ob1;
if (ob1 === ob2) alert('false');
if (ob1 === ob3) alert('true');
ob3.prop3 = 'c';
if (ob1 === ob3) alert('true');
if ('c' === ob1.prop3) alert('true');
Now if you want to re-write an equal method in javascript for 2 different objects having the same properties you should have a look at the following thread on Stackoverflow :
http://stackoverflow.com/questions/1068834/object-comparison-in-javascript
http://ronanquillevere.github.io/2012/12/12/javascript-object-comparison.html
-- old version --
Hello everyone,
Today, working on an elegant message box system for our Sencha Touch mobile application I asked myself the following question : How does the === operator works when comparing objects ?
Well I found this article useful : http://javascript.about.com/od/byexample/a/objectoriented-compareobject-example.htm
The fundamental point is, when you assign an object to a var in javascript, this var is on only a reference to the object. The === comparator will compare the object your reference is pointing on. The following code will only display 'true' values.
var ob1, ob2, ob3;
ob1 = {prop1: 'a', prop2: 'b'};
ob2 = {prop1: 'a', prop2: 'b'};
ob3 = ob1;
if (ob1 === ob2) alert('false');
if (ob1 === ob3) alert('true');
ob3.prop3 = 'c';
if (ob1 === ob3) alert('true');
if ('c' === ob1.prop3) alert('true');
Now if you want to re-write an equal method in javascript for 2 different objects having the same properties you should have a look at the following thread on Stackoverflow :
http://stackoverflow.com/questions/1068834/object-comparison-in-javascript
