FID

This library provides FID(Fully Indexable Dictionary) in JavaScript.

Example

``javascript
var myfid = new FID([0, 1, 1, 0, 1, 0, 1, 1, 1, 0, 1, 1, 1, 0, 0, 1, 1, 1, 1]);
var n = 5;
myfid.rank(n); // 3
myfid.select(3); // 5
``

rank()

rank(n) returns the number of 1 up to position n.

select()

select(n) returns the position of nth 1. (Note: the position which select returns isn't equal to index of Array. the position add 1 is equal to index of Array.)