- Only 2.7 KB minified and gzipped
- Simple API
- Replicates the
- Includes a
- Stores values in an accessible decimal floating point format
- No dependencies
- Comprehensive documentation and test set
It can be loaded via a script tag in an HTML document for the browser
or as a CommonJS, Node.js or AMD module using
var Big = require('big.js');
For Node.js, the library is available from the npm registry:
$ npm install big.js
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
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
(with negative exponent) methods is determined by the value of the
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 reference from the doc folder.
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.
The perf directory contains two applications and a lib directory containing the BigDecimal libraries used by both.
- 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
$ 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.
$ node bigtime -h
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.
tsd query big.js --action install
Any questions about the TypeScript definitions file should be addressed to the DefinitelyTyped project.
Feedback is welcome.
Bugs/comments/questions? Open an issue, or email
Bitcoin donation to: 1DppGRQSjVSMgGxuygDEHQuWEdTiVEzJYG Thank you
- Minor documentation updates.
- README typo.
- API documentation update, including FAQ additions.
- Renamed and exposed
- Remove .npmignore, use
filesfield in package.json instead.
- Clean-up after lint.
- 10/12/14 Added multiple constructor functionality.
- No breaking changes or other additions, but a major code reorganisation, so v3 seemed appropiate.
- 1/11/14 Added bower.json.
- 8/06/14 Amend README requires.
- 26/01/14 Added
toJSONmethod so serialization uses
- 17/10/13 Conform signed zero to IEEEE 754 (2008).
- 19/09/13 Throw instances of
- 16/09/13 Added
- 11/07/13 Added 'round up' mode.
- 26/06/13 Allow e.g.
- 12/05/13 Added
absmethod and replaced
- Changed default value of MAX_DP to 1E6
- 7/11/2012 Initial release