# lb-ratio

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## Ratio.js

Provides a Fraction / Rational / Ratio object for javascript.

Why use Ratio.js?

By keeping values in a rational form, you can maintain precision and can avoid common floating point operation errors in Javascript.

Support:

Node.js, Chrome 19+, Firefox 12+, IE 7+, and Opera 11+.

Note: Run the test cases to check for additional browser compatibility.

##Current version 0.4.1

## Installation

Just include the Ratio.js script. There are no dependencies.

Browser:

``````<script src="./dist/Ratio-0.4.1.js"></script>
``````

Install from npm

``````npm install lb-ratio
``````

Include in project

``````var Ratio = require("lb-ratio");
``````

## Development

Useful npm scripts. First run `npm install` on the root directory.

• `npm run format` : Format the javascript code in `./lib` with jsbeautifier.
• `npm run lint` : Lint code with jshint and find errors in the code.
• `npm run build` : Build a release based on base package.json version number and the beta js.

## Examples

1. What is `12.12121212121212` as a fraction?

Solution:

``````var result = Ratio.parse( 12.12121212121212 ).simplify().toString();
result === "400/33";
``````
2. Evaluate ( 0.1 + 0.2 )/( 1/3 * 12 )?

Solution:

``````var a = Ratio.parse(0.1).add(0.2).divide( Ratio(1,3).multiply(12) );
var result = a.toString();
result === "3/40"
``````
3. Does Math.PI equal 22/7?

Solution:

``````var result = Ratio.parse( "22/7" ).equals( Math.PI );
result === false;
``````

## Short Tutorial

### Ratio Constructor

Ratio.js introduces a global constructor called `Ratio`.

`new` is not require to make a new object since it's done for you.
Thus `new Ratio()` and `Ratio()` are both valid to instantiate an object.

### Ratio Properties

The default value of the numerator is 0 and denominator is 1.

``````var a = Ratio();
a.toString() === "0/1";
a.numerator() === 0;
a.denominator() === 1;
``````

Examples:

``````// Good Values
Ratio().toString() === "0/1"
Ratio(4).toString() === "4/1"
Ratio(4,5).toString() === "4/5"

Ratio("five").toString() === "NaN/1"
Ratio(1,"ten").toString() === "1/NaN"
Ratio("five","ten").toString() === "NaN/NaN"
``````

### Ratio values

To retrieve the value inside a Ratio object you can use `toString()`, `toLocaleString()`, `toArray()` or `valueOf()`.
`toString()` - returns string "numerator/denominator".
`toArray()` - returns [ numerator, denominator ].
`valueOf()` - returns (numerator/denominator).
`toLocaleString()` - returns string mixed number, whole number or proper fraction.

``````var a = Ratio(30,10);
a.toString() === "30/10";
a.toLocaleString() === "3";
a.toArray() // returns [30,10];
a.valueOf() === 3; // same as +a or Number(a)
``````

### Ratio Comparison

valueOf() is called when inequality comparisons are made on a Ratio object.
However, equalivance( `==` ) will compare the object and not the value of the object. Use `.equals()` instead.
Thus you can do the following.

``````var a = Ratio(15,3),
b = Ratio(3,15);

(a > b) === true;
(a < b) === false;
( a == b ) === false;
a.equals( a ) === true;
a.equals( b ) === false;
``````

### Creating new Ratio Objects

There are various ways to create a new Ratio object. Ratio.parse() is the prefered methods.

`Ratio()`

``````// "0/1" is the default ratio
Ratio().toString() === "0/1";

// Accepts whole numbers
Ratio(1).toString() === "1/1";

// Accepts an numerator and denominator
Ratio(1,2).toString() === "1/2";
``````

`Ratio.parse( value )`

``````// Use Ratio.parse() to parse any other values that aren't whole numbers.

// Accepts decimals
Ratio.parse(1/2).toString() === "1/2";

// Accepts fractions as strings
Ratio.parse("1/2").toString() === "1/2";

// Accepts mixed numbers as strings
Ratio.parse( "1 1/2" ).toString() === "3/2";

// Accepts a Ratio object
Ratio.parse( Ratio(1/2) ).toString() === "1/2";
``````

`Ratio.parse( value1, value2 )`
This is the same as `value1 / value2` or `Ratio.parse(value1).divide(value2)`

``````// Converts the Ratio objects to a single fraction.
Ratio.parse( Ratio(1), Ratio(2) ).toString() === "1/2";

// Accepts
// (1/2) / (1/3) = 3/2
Ratio.parse( "1/2", "1/3" ).toString() === "3/2";

``````

### Methods

All proproty methods are non-destructive and return a new Ratio object.

``````var a = Ratio(1,3);
a.toString() === "1/3"
a.toString() === "1/3"
``````

Refer to the documentation for a complete method list.

``````// in Javascript
var a = 0.1 + 0.2;
var b = 0.3;
( a == b ) === false;
a === 0.30000000000000004;

var a = Ratio();
a.toString() === "0/1";

// Ratio operations
c.toString() === "1053/5";

// in Ratio.js
var a = Ratio( 0.1 ).add( 0.2 );
var b = Ratio( 0.3 );
(+a == +b ) === true;

// another way of writing it.
Ratio( "0.1" ).add( 0.2 ).equals( 0.3 ); // true!

// And another.
var a = Ratio(1,10);
var b = Ratio(2,10);
var c = Ratio(3,10);
a.add( b ).toString() === c.toString(); // true!

a.toString() === "1/10";
+a === 0.1;
( +a === a.valueOf() ) ;
a.toArray(); // returns [ 1, 10 ]
``````

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