Why when I create a new model and try to retrieve its ID

Why when I create a new model and try to retrieve its ID

References

Reference NO 1

http://backbonejs.org/

Reference NO 2

https://docs.djangoproject.com/en/dev/ref/models/querysets/

Reference NO 3

http://mongoosejs.com/docs/api.html

Reference NO 4

http://support.apple.com/kb/HT5570

Reference NO 5

http://www.quirksmode.org/dom/intro.html

Reference NO 6

http://stackoverflow.com/questions/14685793/how-to-get-the-latest-inserted-id-for-a-model-in-backbonejs

Reference NO 7

https://developers.google.com/appengine/docs/python/datastore/modelclass

Reference NO 8

https://stripe.com/docs/api