JavaScript class for processing fractions
RationalNumber is an implementation of rational numbers in JavaScript that manages fractions consisting of two integers. Mathematical operations such as addition, subtraction, multiplication and division are provided. Division by zero is allowed and should produce correct mathematical results according to the use of Infinity and NaN in JavaScript.
Fractions are maintained by default in reduced form. For example, setting the value to 2/4 will automatically be reduced (simplified) to 1/2. However functions for forcing nonreduced fractions are provided, particularly for avoiding speed issues in intermediate calculations (although the current mathematical functions will reduce the fraction after every calculation to minimize the chance of overflow).
This implementation limits the numerator and denominator to the
range from 0 to 2^{53}–1 plus a sign, and optional
automatic overflow detection is included by running checkOverflowOn()
,
and CheckOverflowOff()
turning this feature off.
The following section uses the RationalNumber Javascript code to dynamically process rational numbers. Try typing various values in the four boxes below to create rational numbers. The reduced forms of the number will be shown to the right, and example mathematical calculations using the two rational numbers is given further below. Try typing a very large number to see what happens when any number has an absolute value greater or equal to 2^{53}.

 


Addition:  
Subtraction:  
Multiplication:  
Division: 
This code can be installed globally for use in node with the command:
$ npm install g rationalnumber
If you want to install locally within anode project, then install as a package dependency with the command:
$ npm install save rationalnumber
Here is an code example which loads the module into a node script, creates two RationalNumbers (4/5 and 13/2), adds them, and then prints the result to the console:
var RationalNumber = require('rationalnumber');
var rn1 = new RationalNumber(4, 5);
var rn2 = new RationalNumber('26/4');
var rn3 = rn1.add(rn2);
console.log(rn1.toString(),"+",rn2.toString(),"=",rn3.toString());
console.log(rn1.toStringMixed("_"),"+",rn2.toStringMixed("_"),
"=",rn3.toStringMixed("_"));
console.log(rn1.valueOf()+" + "+rn2.valueOf()+" = "+rn3.valueOf());
The above code should output the following text to the console:
4/5 + 13/2 = 73/10
4/5 + 6_1/2 = 7_3/10
0.8 + 6.5 = 7.3
The JavaScript code for rational numbers can also be used standalone within a webpage by including these two files:
<script src="RationalNumberbase.js"></script>
<script src="RationalNumbermath.js"></script>
The first file (RationalNumberbase.js) is required, while the second one containing mathematical functions (add, subtract, etc.) is optional. The RationalNumber repository's lib directory contains a makefile with example commands to generate minified versions of the JavaScript programs.
Input and output from the RationalNumber code can be tested using
mocha and the JavaScript files in the test
directory of the repository. To test from a node installation:
$ npm install # to download mocha dependency if necessary
$ npm test
If you have mocha installed globally in your
search path (such as with "npm install g mocha
"), you can also
type one of the following equivalent shell commands to run the code
tests:
$ make test
$ mocha test
$ cd test; make
$ cd test; mocha
Click on the entries below to view documentation and examples for each RationalNumber method. Code examples can be run in the JavaScript console for this page since it has already loaded a copy of the RationalNumber code. Press ctrl + +/= to open all documentation, ctrl+– to close all documentation, and ctrl+e to toggle display of all code examples. shft+click will open documentation for a single method and close all other entries.
The following RationalNumber methods provide additional arithmetic processing from the optional RationalNumbermath.js file: