If a smaller and simpler library is required see [big.js](https://github.com/MikeMcl/big.js/).
It's less than half the size but only works with decimal numbers and only has half the methods.
It also does not allow `NaN` or `Infinity`, or have the configuration options of this library.
See also [decimal.js](https://github.com/MikeMcl/decimal.js/), which among other things adds support for non-integer powers, and performs all operations to a specified number of significant digits.
## Load
The library is the single JavaScript file *bignumber.js* (or minified, *bignumber.min.js*).
Like JavaScript's number type, there are `toExponential`, `toFixed` and `toPrecision` methods
```javascript
x = new BigNumber(255.5)
x.toExponential(5) // "2.55500e+2"
x.toFixed(5) // "255.50000"
x.toPrecision(5) // "255.50"
x.toNumber() // 255.5
```
and a base can be specified for `toString`.
```javascript
x.toString(16) // "ff.8"
```
There is also a `toFormat` method which may be useful for internationalisation
```javascript
y = new BigNumber('1234567.898765')
y.toFormat(2) // "1,234,567.90"
```
The maximum number of decimal places of the result of an operation involving division (i.e. a division, square root, base conversion or negative power operation) is set using the `config` method of the `BigNumber` constructor.
The other arithmetic operations always give the exact result.
Multiple BigNumber constructors can be created, each with their own independent configuration which applies to all BigNumber's created from it.
```javascript
// Set DECIMAL_PLACES for the original BigNumber constructor
BigNumber.config({ DECIMAL_PLACES: 10 })
// Create another BigNumber constructor, optionally passing in a configuration object
BN = BigNumber.another({ DECIMAL_PLACES: 5 })
x = new BigNumber(1)
y = new BN(1)
x.div(3) // '0.3333333333'
y.div(3) // '0.33333'
```
For futher information see the [API](http://mikemcl.github.io/bignumber.js/) reference in the *doc* directory.
## Test
The *test* directory contains the test scripts for each method.
The tests can be run with Node or a browser. For Node use
$ npm test
or
$ node test/every-test
To test a single method, e.g.
$ node test/toFraction
For the browser, see *every-test.html* and *single-test.html* in the *test/browser* directory.
*bignumber-vs-number.html* enables some of the methods of bignumber.js to be compared with those of JavaScript's number type.
## Versions
This is version 2.x.x of the library, for version 1.x.x see the tagged releases or switch to the 'original' branch. The advantages of version 2 are that it is considerably faster for numbers with many digits and that there are a some added methods (see Change Log below). The disadvantages are more lines of code and increased code complexity, and the loss of simplicity in no longer having the coefficient of a BigNumber stored in base 10. The 'original' version will continue to be supported.
## Performance
See the [README](https://github.com/MikeMcl/bignumber.js/tree/master/perf) in the *perf* directory.
## Build
For Node, if [uglify-js](https://github.com/mishoo/UglifyJS2) is installed
npm install uglify-js -g
then
npm run build
will create *bignumber.min.js*.
A source map will also be created in the root directory.
