previousAttributes

优质

小牛编辑

147浏览

2023-12-01

描述 (Description)

它会在上次更改事件之前返回模型先前属性的副本。这对于在模型版本之间获取差异或在发生错误后返回有效状态非常有用。

语法 (Syntax)

model.previousAttributes()

例子 (Example)

<!DOCTYPE html>
   <head>
      <title>Model 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({
            id:01,
            player:'Sachin',
            country:'India'
         });
         model.set('id', '02');
         document.write(
            "All the attributes returned by the previousAttributes() method are: ");
         document.write("<br>");
         document.write(JSON.stringify(model.previousAttributes()));
      </script>
   </body>
</html>