How to make web app that loads in the same way like flipkart or amazon?

Basically i want to know which technology or language these webapp uses?

I want to achieve following:

• Main content should load first and secondary content should loads in background after main content finished loading.
• Tertiary content should load only on scroll

What i know and do not want to use :

• Basic ajax call
  1. When main content load, fire ajax call for secondary content
  2. Fire ajax call for tertiary content when user scroll

I am open to use any technologies

via Rakesh Soni