363 lines
11 KiB
Markdown
363 lines
11 KiB
Markdown
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A JavaScript library for arbitrary-precision decimal and non-decimal arithmetic.
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[](https://travis-ci.org/MikeMcl/bignumber.js)
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<br />
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## Features
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- Faster, smaller, and perhaps easier to use than JavaScript versions of Java's BigDecimal
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- 8 KB minified and gzipped
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- Simple API but full-featured
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- Works with numbers with or without fraction digits in bases from 2 to 64 inclusive
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- Replicates the `toExponential`, `toFixed`, `toPrecision` and `toString` methods of JavaScript's Number type
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- Includes a `toFraction` and a correctly-rounded `squareRoot` method
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- Supports cryptographically-secure pseudo-random number generation
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- No dependencies
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- Wide platform compatibility: uses JavaScript 1.5 (ECMAScript 3) features only
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- Comprehensive [documentation](http://mikemcl.github.io/bignumber.js/) and test set
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If a smaller and simpler library is required see [big.js](https://github.com/MikeMcl/big.js/).
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It's less than half the size but only works with decimal numbers and only has half the methods.
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It also does not allow `NaN` or `Infinity`, or have the configuration options of this library.
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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.
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## Load
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The library is the single JavaScript file *bignumber.js* (or minified, *bignumber.min.js*).
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```html
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<script src='relative/path/to/bignumber.js'></script>
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```
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For [Node.js](http://nodejs.org), the library is available from the [npm](https://npmjs.org/) registry
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$ npm install bignumber.js
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```javascript
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var BigNumber = require('bignumber.js');
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```
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To load with AMD loader libraries such as [requireJS](http://requirejs.org/):
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```javascript
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require(['path/to/bignumber'], function(BigNumber) {
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// Use BigNumber here in local scope. No global BigNumber.
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});
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```
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## Use
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*In all examples below, `var`, semicolons and `toString` calls are not shown.
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If a commented-out value is in quotes it means `toString` has been called on the preceding expression.*
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The library exports a single function: `BigNumber`, the constructor of BigNumber instances.
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It accepts a value of type number *(up to 15 significant digits only)*, string or BigNumber object,
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```javascript
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x = new BigNumber(123.4567)
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y = BigNumber('123456.7e-3')
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z = new BigNumber(x)
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x.equals(y) && y.equals(z) && x.equals(z) // true
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```
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and a base from 2 to 64 inclusive can be specified.
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```javascript
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x = new BigNumber(1011, 2) // "11"
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y = new BigNumber('zz.9', 36) // "1295.25"
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z = x.plus(y) // "1306.25"
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```
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A BigNumber is immutable in the sense that it is not changed by its methods.
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```javascript
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0.3 - 0.1 // 0.19999999999999998
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x = new BigNumber(0.3)
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x.minus(0.1) // "0.2"
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x // "0.3"
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```
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The methods that return a BigNumber can be chained.
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```javascript
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x.dividedBy(y).plus(z).times(9).floor()
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x.times('1.23456780123456789e+9').plus(9876.5432321).dividedBy('4444562598.111772').ceil()
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```
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Many method names have a shorter alias.
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```javascript
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x.squareRoot().dividedBy(y).toPower(3).equals(x.sqrt().div(y).pow(3)) // true
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x.cmp(y.mod(z).neg()) == 1 && x.comparedTo(y.modulo(z).negated()) == 1 // true
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```
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Like JavaScript's number type, there are `toExponential`, `toFixed` and `toPrecision` methods
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```javascript
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x = new BigNumber(255.5)
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x.toExponential(5) // "2.55500e+2"
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x.toFixed(5) // "255.50000"
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x.toPrecision(5) // "255.50"
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x.toNumber() // 255.5
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```
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and a base can be specified for `toString`.
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```javascript
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x.toString(16) // "ff.8"
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```
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There is also a `toFormat` method which may be useful for internationalisation
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```javascript
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y = new BigNumber('1234567.898765')
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y.toFormat(2) // "1,234,567.90"
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```
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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.
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The other arithmetic operations always give the exact result.
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```javascript
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BigNumber.config({ DECIMAL_PLACES: 10, ROUNDING_MODE: 4 })
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// Alternatively, BigNumber.config( 10, 4 );
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x = new BigNumber(2);
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y = new BigNumber(3);
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z = x.div(y) // "0.6666666667"
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z.sqrt() // "0.8164965809"
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z.pow(-3) // "3.3749999995"
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z.toString(2) // "0.1010101011"
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z.times(z) // "0.44444444448888888889"
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z.times(z).round(10) // "0.4444444445"
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```
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There is a `toFraction` method with an optional *maximum denominator* argument
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```javascript
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y = new BigNumber(355)
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pi = y.dividedBy(113) // "3.1415929204"
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pi.toFraction() // [ "7853982301", "2500000000" ]
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pi.toFraction(1000) // [ "355", "113" ]
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```
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and `isNaN` and `isFinite` methods, as `NaN` and `Infinity` are valid `BigNumber` values.
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```javascript
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x = new BigNumber(NaN) // "NaN"
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y = new BigNumber(Infinity) // "Infinity"
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x.isNaN() && !y.isNaN() && !x.isFinite() && !y.isFinite() // true
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```
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The value of a BigNumber is stored in a decimal floating point format in terms of a coefficient, exponent and sign.
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```javascript
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x = new BigNumber(-123.456);
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x.c // [ 123, 45600000000000 ] coefficient (i.e. significand)
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x.e // 2 exponent
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x.s // -1 sign
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```
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Multiple BigNumber constructors can be created, each with their own independent configuration which applies to all BigNumber's created from it.
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```javascript
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// Set DECIMAL_PLACES for the original BigNumber constructor
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BigNumber.config({ DECIMAL_PLACES: 10 })
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// Create another BigNumber constructor, optionally passing in a configuration object
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BN = BigNumber.another({ DECIMAL_PLACES: 5 })
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x = new BigNumber(1)
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y = new BN(1)
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x.div(3) // '0.3333333333'
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y.div(3) // '0.33333'
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```
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For futher information see the [API](http://mikemcl.github.io/bignumber.js/) reference in the *doc* directory.
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## Test
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The *test* directory contains the test scripts for each method.
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The tests can be run with Node or a browser. For Node use
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$ npm test
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or
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$ node test/every-test
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To test a single method, e.g.
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$ node test/toFraction
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For the browser, see *every-test.html* and *single-test.html* in the *test/browser* directory.
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*bignumber-vs-number.html* enables some of the methods of bignumber.js to be compared with those of JavaScript's number type.
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## Versions
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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.
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## Performance
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See the [README](https://github.com/MikeMcl/bignumber.js/tree/master/perf) in the *perf* directory.
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## Build
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For Node, if [uglify-js](https://github.com/mishoo/UglifyJS2) is installed
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npm install uglify-js -g
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then
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npm run build
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will create *bignumber.min.js*.
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A source map will also be created in the root directory.
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## Feedback
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Open an issue, or email
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Michael
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<a href="mailto:M8ch88l@gmail.com">M8ch88l@gmail.com</a>
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## Licence
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MIT.
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See [LICENCE](https://github.com/MikeMcl/bignumber.js/blob/master/LICENCE).
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## Change Log
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####2.4.0
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* 14/07/2016
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* #97 Add exports to support ES6 imports.
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####2.3.0
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* 07/03/2016
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* #86 Add modulus parameter to `toPower`.
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####2.2.0
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* 03/03/2016
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* #91 Permit larger JS integers.
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####2.1.4
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* 15/12/2015
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* Correct UMD.
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####2.1.3
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* 13/12/2015
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* Refactor re global object and crypto availability when bundling.
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####2.1.2
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* 10/12/2015
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* Bugfix: `window.crypto` not assigned to `crypto`.
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####2.1.1
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* 09/12/2015
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* Prevent code bundler from adding `crypto` shim.
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####2.1.0
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* 26/10/2015
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* For `valueOf` and `toJSON`, include the minus sign with negative zero.
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####2.0.8
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* 2/10/2015
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* Internal round function bugfix.
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####2.0.6
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* 31/03/2015
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* Add bower.json. Tweak division after in-depth review.
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####2.0.5
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* 25/03/2015
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* Amend README. Remove bitcoin address.
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####2.0.4
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* 25/03/2015
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* Critical bugfix #58: division.
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####2.0.3
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* 18/02/2015
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* Amend README. Add source map.
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####2.0.2
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* 18/02/2015
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* Correct links.
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####2.0.1
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* 18/02/2015
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* Add `max`, `min`, `precision`, `random`, `shift`, `toDigits` and `truncated` methods.
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* Add the short-forms: `add`, `mul`, `sd`, `sub` and `trunc`.
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* Add an `another` method to enable multiple independent constructors to be created.
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* Add support for the base 2, 8 and 16 prefixes `0b`, `0o` and `0x`.
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* Enable a rounding mode to be specified as a second parameter to `toExponential`, `toFixed`, `toFormat` and `toPrecision`.
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* Add a `CRYPTO` configuration property so cryptographically-secure pseudo-random number generation can be specified.
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* Add a `MODULO_MODE` configuration property to enable the rounding mode used by the `modulo` operation to be specified.
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* Add a `POW_PRECISION` configuration property to enable the number of significant digits calculated by the power operation to be limited.
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* Improve code quality.
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* Improve documentation.
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####2.0.0
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* 29/12/2014
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* Add `dividedToIntegerBy`, `isInteger` and `toFormat` methods.
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* Remove the following short-forms: `isF`, `isZ`, `toE`, `toF`, `toFr`, `toN`, `toP`, `toS`.
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* Store a BigNumber's coefficient in base 1e14, rather than base 10.
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* Add fast path for integers to BigNumber constructor.
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* Incorporate the library into the online documentation.
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####1.5.0
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* 13/11/2014
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* Add `toJSON` and `decimalPlaces` methods.
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####1.4.1
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* 08/06/2014
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* Amend README.
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####1.4.0
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* 08/05/2014
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* Add `toNumber`.
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####1.3.0
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* 08/11/2013
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* Ensure correct rounding of `sqrt` in all, rather than almost all, cases.
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* Maximum radix to 64.
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####1.2.1
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* 17/10/2013
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* Sign of zero when x < 0 and x + (-x) = 0.
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####1.2.0
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* 19/9/2013
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* Throw Error objects for stack.
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####1.1.1
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* 22/8/2013
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* Show original value in constructor error message.
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####1.1.0
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* 1/8/2013
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* Allow numbers with trailing radix point.
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####1.0.1
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* Bugfix: error messages with incorrect method name
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####1.0.0
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* 8/11/2012
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* Initial release
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