Backbone.js model.previousAttributes()

The Backbone.js PreviousAttributes model returns the model's previous attributes before the last change event. It is used to get the difference between the versions of a model, or restore the previous attributes after an error occurs.

Syntax:

Let's take an example.

See this example:

  <!DOCTYPE html>
   <head>
      <title>PreviousAttributes Example</title>
         <script src="https://code.jquery.com/jquery-2.1.3.min.js" type="text/javascript"></script>
         <script src="https://cdnjs.cloudflare.com/ajax/libs/underscore.js/1.8.2/underscore-min.js" type="text/javascript"></script>
         <script src="https://cdnjs.cloudflare.com/ajax/libs/backbone.js/1.1.2/backbone-min.js" type="text/javascript"></script>
   </head>
   <body>
   <script type="text/javascript">
      var model = new Backbone.Model({
         jersey:10,
         player:'Dhoni',
         country:'India'
      });
      model.set('jersey', '99');
      document.write("All the attributes returned by the previousAttributes() method are: ");
      document.write("<br>");
      document.write(JSON.stringify(model.previousAttributes()));
   </script>
   </body>
</html>

Test it Now

Output:

Save the above code in previousattributes.html file and open this file in a new browser.