# big.js #
A small, fast JavaScript library for arbitrary-precision decimal arithmetic.
The little sister to [bignumber.js](https://github.com/MikeMcl/bignumber.js/).
See also [decimal.js](https://github.com/MikeMcl/decimal.js/), and [here](https://github.com/MikeMcl/big.js/wiki) for the difference between them.
## Features
- Faster, smaller and easier-to-use than JavaScript versions of Java's BigDecimal
- Only 2.7 KB minified and gzipped
- Simple API
- Replicates the `toExponential`, `toFixed` and `toPrecision` methods of JavaScript's Number type
- Includes a `sqrt` method
- Stores values in an accessible decimal floating point format
- No dependencies
- Comprehensive [documentation](http://mikemcl.github.io/big.js/) and test set
## Load
The library is the single JavaScript file *big.js* (or *big.min.js*, which is *big.js* minified).
It can be loaded via a script tag in an HTML document for the browser
<script src='./relative/path/to/big.js'></script>
or as a CommonJS, [Node.js](http://nodejs.org) or AMD module using `require`.
var Big = require('big.js');
For Node.js, the library is available from the npm registry:
$ npm install big.js
## Use
*In all examples below, `var`, semicolons and `toString` calls are not shown.
If a commented-out value is in quotes it means `toString` has been called on the preceding expression.*
The library exports a single function: Big, the constructor of Big number instances.
It accepts a value of type Number, String or Big number Object.
x = new Big(123.4567)
y = Big('123456.7e-3') // 'new' is optional
z = new Big(x)
x.eq(y) && x.eq(z) && y.eq(z) // true
A Big number is immutable in the sense that it is not changed by its methods.
0.3 - 0.1 // 0.19999999999999998
x = new Big(0.3)
x.minus(0.1) // "0.2"
x // "0.3"
The methods that return a Big number can be chained.
x.div(y).plus(z).times(9).minus('1.234567801234567e+8').plus(976.54321).div('2598.11772')
x.sqrt().div(y).pow(3).gt(y.mod(z)) // true
Like JavaScript's Number type, there are `toExponential`, `toFixed` and `toPrecision` methods.
x = new Big(255.5)
x.toExponential(5) // "2.55500e+2"
x.toFixed(5) // "255.50000"
x.toPrecision(5) // "255.50"
The maximum number of decimal places and the rounding mode used to round the results of the `div`, `sqrt` and `pow`
(with negative exponent) methods is determined by the value of the `DP` and `RM` properties of the `Big` number constructor.
The other methods always give the exact result.
(From *v3.0.0*, multiple Big number constructors can be created, see Change Log below.)
Big.DP = 10
Big.RM = 1
x = new Big(2);
y = new Big(3);
z = x.div(y) // "0.6666666667"
z.sqrt() // "0.8164965809"
z.pow(-3) // "3.3749999995"
z.times(z) // "0.44444444448888888889"
z.times(z).round(10) // "0.4444444445"
The value of a Big number is stored in a decimal floating point format in terms of a coefficient, exponent and sign.
x = new Big(-123.456);
x.c // [1,2,3,4,5,6] coefficient (i.e. significand)
x.e // 2 exponent
x.s // -1 sign
For further information see the [API](http://mikemcl.github.io/big.js/) reference from the *doc* folder.
## Test
The *test* directory contains the test scripts for each Big number method.
The tests can be run with Node or a browser.
To test a single method, from a command-line shell at the *test* directory, use e.g.
$ node toFixed
To test all the methods
$ node every-test
For the browser, see *single-test.html* and *every-test.html* in the *test/browser* directory.
*big-vs-number.html* enables some of the methods of big.js to be compared with those of JavaScript's Number type.
## Performance
The *perf* directory contains two applications and a *lib* directory containing the BigDecimal libraries used by both.
*big-vs-bigdecimal.html* tests the performance of big.js against the JavaScript translations of two versions of BigDecimal, its use should be more or less self-explanatory.
(The GWT version doesn't work in IE 6.)
* GWT: java.math.BigDecimal
<https://github.com/iriscouch/bigdecimal.js>
* ICU4J: com.ibm.icu.math.BigDecimal
<https://github.com/dtrebbien/BigDecimal.js>
The BigDecimal in Node's npm registry is the GWT version. Despite its seeming popularity I have found it to have some serious bugs, see the Node script *perf/lib/bigdecimal_GWT/bugs.js* for examples of flaws in its *remainder*, *divide* and *compareTo* methods.
*bigtime.js* is a Node command-line application which tests the performance of big.js against the GWT version of
BigDecimal from the npm registry.
For example, to compare the time taken by the big.js `plus` method and the BigDecimal `add` method:
$ node bigtime plus 10000 40
This will time 10000 calls to each, using operands of up to 40 random digits and will check that the results match.
For help:
$ node bigtime -h
## Build
I.e. minify.
For Node, if uglify-js is installed globally ( `npm install uglify-js -g` ) then
uglifyjs -o ./big.min.js ./big.js
will create *big.min.js*.
The *big.min.js* already present was created with *Microsoft Ajax Minifier 5.11*.
## TypeScript
The [DefinitelyTyped](https://github.com/borisyankov/DefinitelyTyped) project has a TypeScript [definitions file](https://github.com/borisyankov/DefinitelyTyped/blob/master/big.js/big.js.d.ts) for big.js.
The definitions file can be added to your project via the [big.js.TypeScript.DefinitelyTyped](https://www.nuget.org/packages/big.js.TypeScript.DefinitelyTyped/0.0.1) NuGet package or via [tsd](http://definitelytyped.org/tsd/).
tsd query big.js --action install
Any questions about the TypeScript definitions file should be addressed to the DefinitelyTyped project.
## Feedback
Feedback is welcome.
Bugs/comments/questions?
Open an issue, or email
Michael
<a href="mailto:M8ch88l@gmail.com">M8ch88l@gmail.com</a>
Bitcoin donation to:
**1DppGRQSjVSMgGxuygDEHQuWEdTiVEzJYG**
Thank you
## Licence
See LICENCE.
## Change Log
####3.2.0
* 14/09/17 Aid ES6 import.
####3.1.3
* Minor documentation updates.
####3.1.2
* README typo.
####3.1.1
* API documentation update, including FAQ additions.
####3.1.0
* Renamed and exposed `TO_EXP_NEG` and `TO_EXP_POS` as `Big.E_NEG` and
`Big.E_POS`.
####3.0.2
* Remove *.npmignore*, use `files` field in *package.json* instead.
####3.0.1
* Added `sub`, `add` and `mul` aliases.
* Clean-up after lint.
####3.0.0
* 10/12/14 Added [multiple constructor functionality](http://mikemcl.github.io/big.js/#faq).
* No breaking changes or other additions, but a major code reorganisation,
so *v3* seemed appropriate.
####2.5.2
* 1/11/14 Added bower.json.
####2.5.1
* 8/06/14 Amend README requires.
####2.5.0
* 26/01/14 Added `toJSON` method so serialization uses `toString`.
####2.4.1
* 17/10/13 Conform signed zero to IEEEE 754 (2008).
####2.4.0
* 19/09/13 Throw instances of `Error`.
####2.3.0
* 16/09/13 Added `cmp` method.
####2.2.0
* 11/07/13 Added 'round up' mode.
####2.1.0
* 26/06/13 Allow e.g. `.1` and `2.`.
####2.0.0
* 12/05/13 Added `abs` method and replaced `cmp` with `eq`, `gt`, `gte`, `lt`, and `lte` methods.
####1.0.1
* Changed default value of MAX_DP to 1E6
####1.0.0
* 7/11/2012 Initial release