Talking about the defaults of backbone

The use of backbone development also has a period of time, until the first 2 weeks, only to find that the previous walk is a detour, the use of the way is wrong.

It's not a rip. Keep track of what you need to be aware of when you use backbone's defaults today.

As backbone knows, defaults can save a lot of repetitive initialization code snippets.

1 var Model = Backbone.Model.extend ({2    defaults: {3         str: ' This is String ',  4         num:05    }6}); 7 8 var a=New  Model (); 9 var b=New Model ();

Then try the following code

1 varModel =Backbone.Model.extend ({2 defaults: {3 list: [],4 obj: {}5     }6 });7 8 varA =NewModel ();9 varb =NewModel ();Ten  OneA.get (' list '). Push (1); AA.get (' obj ') [' str '] = ' tihs is String '; -  -Console.log ("B.attributes", b.attributes);

The results are as follows

Yes, the data for Model B is also changed for simple reasons: Array and object are reference types.

There are 2 solutions:

1, when initializing an object, explicitly passing in the initialized data

1 var New Model ({list: [], obj: {}}); 2 var New Model ({list: [], obj: {}});

2, modify the value of the Defaults object, return by function

1 var Model = Backbone.Model.extend ({2     function  () {3         return  {4            list: [],5            obj: {}6         }; 7     }8 });

Look at the model method of backbone

1   varModel = Backbone.model =function(attributes, options) {2     varattrs = Attributes | | {};3Options | | (options = {});4      This. CID = _.uniqueid (' C ');5      This. attributes = {};6     if(options.collection) This. Collection =options.collection;7     if(options.parse) Attrs = This. Parse (attrs, options) | | {};8Attrs = _.defaults ({}, Attrs, _.result ( This, ' defaults '));9      This. Set (attrs, options);Ten      This. changed = {}; One      This. initialize.apply ( This, arguments); A};

The focus is: Attrs = _.defaults ({}, Attrs, _.result (this, ' defaults '));

One of the underscore methods _.result

Just remind yourself: do not look at the document on the line, regardless of the source code. Really can't be lazy again!

Talking about the defaults of backbone