when two range sliders are on the same page id #handle-one and #handle-two are not unique.

[martinfrances107]

I have found a semantic issue when I try and place two range sliders on the same page. In short some elements reuse what is supposed to be a unique id.

Looking at the demo page

http://benheb.github.io/d3.slider/

the range slider created by

d3.slider().value([10, 25 ])

here is an edited outline of the HTML

.. ..

When there are two sliders on the page there will be 2 elements with unique id "handle-one" and two elements with id "handle-two"

The solution is to change the id attributes into class attributes - and then tighten up the select of element in the code where appropriate.

I really like this project and will try and find the time to work on the solution soon...but thought I should outline the issue.

[martinfrances107]

This pull request fixes the issue.