Q:

How to calculate approximately the connection speed of a website using JavaScript? 

How to calculate approximately the connection speed of a website using JavaScript? 
I want to create a javascript widget like, which will calculate the speed opening the current opened page. 
I am asking if this can be done using just javascript and what will be the idea. 
Update
Note that the page size is always Unknown. 

A:

Here's an example using AJAX with .Net backend, though it could be anything. 
Here's a simpler example using an image. 
The key is to have a page/object of a known size and capture the start and end times as the browser retrieves it.   Then simply divide the size by some [unit of time] to get [size] per [unit of time].   Then use math to translate this into whatever you want.