rationals
extended rational number type for javascript
Why I think this lib is great:

Representing fractions is not just easy, but it's natural. This is what rational numbers do best. Operations like
0.1 + 0.2
are a pain in js, but using rational numbers, it's just:r(1,10).plus(1,5) === r(3,10)

This lib provides a type of object which will work with 1/0 or 0/0 just as well. This is especially useful if you plan to plot values on a graph.
I've got the inspiration for this lib from here: MF105: The extended rational numbers in practice
Support
Examples
var r = require('rationals');
// denominator of 1 is optional
r(1) === r(1); // true
r(1,1) === r(1); // true
// all rationals will be always reduced
r(2,4) === r(13,26); // true
r(100,50) === r(2); // true
// chaining works
r(1,2).plus(r(1,3)).minus(r(1,4)).times(r(1,5)).per(r(1,6)) === r(49,70); // true
// my personal favorite aproximation of Pi, from ancient china
r(355,113).val(); // 3.1415929203539825
// you can give floats and they will be converted into rationals
rats(0.4,0.1) == rats(4);
API
 a & b are objects created with the rationals() function
 in the parentheses you have some common aliases for the methods
Addition

add (plus)
a.add(b)
Subtraction

subtract (minus, sub)
a.sub(b)
Multiplication

multiply (times, mul)
a.mul(b)
Division

divide (per, div)
a.div(b)
Examining

toString
Examining an object can be hard, but if you cast it to a string:
r(355,113)+''
will return'355/113'
.So
r(625,125).toString()
will return'5/1'
.
Display

display
Just like toString(), but the numerator will be shown only if it's not 1. That is, integers will appear without a slash symbol and a denominator.
r(625,125).display()
returns'5'
.
Approximation

val (value)
Will return the numerator divided with the denominator.
r(355,113).val(); //3.1415929203539825
Ordering

compare (value)
Will return 1, 0 or 1 if the rational is smaller, equal or larger than the rational it is compared to
r(999,605).compare(R(272,835)) // 1
r(966,743).compare(R(632,198)) // 1
r(3,9).compare(R(12,36)) // 0
Compare absolute values

compareAbs (value)
Same as compare but without signs.
r(999,605).compareAbs(R(272,835)) // 1
Good to know
If you provide anything else as the numerator, than an integer, float or a numerica string an exception will be thrown. On the other hand, if you do the same with the denominator, it will be cast to 1. This is because I am lazy, and I do not want to handle wrong values and undefined values differently throwing for the former and casting to 1 for the latter.
Install
npm install rationals
You can use it in the browser with browserify