big-integer

BigInteger.js

BigInteger.js is an arbitrary-length integer library for Javascript, allowing arithmetic operations on integers of unlimited size, notwithstanding memory and time limitations.

If you are using a browser, you can download BigInteger.js from GitHub or just hotlink to it:

<script src="http://peterolson.github.com/BigInteger.js/BigInteger.min.js"></script>

If you are using node, you can install BigInteger with npm.

npm install big-integer

Then you can include it in your code:

var bigInt = require("big-integer");

The unit tests are contained in the BigInteger.test.js file. You can run them online from GitHub.

bigInt(number, [base])

You can create a bigInt by calling the bigInt function. You can pass in

• a string, which it will parse as an bigInt and throw an "Invalid integer" error if the parsing fails.
• a Javascript number, which it will parse as an bigInt and throw an "Invalid integer" error if the parsing fails.
• another bigInt.
• nothing, and it will return bigInt.zero.

If you provide a second parameter, then it will parse number as a number in base base. Note that base can be any bigInt (even negative or zero). The letters "a-z" and "A-Z" will be interpreted as the numbers 10 to 36. Higher digits can be specified in angle brackets (< and >).

Examples:

var zero = bigInt();
var ninetyThree = bigInt(93);
var largeNumber = bigInt("75643564363473453456342378564387956906736546456235345");
var googol = bigInt("1e100");
var bigNumber = bigInt(largeNumber);
 
var maximumByte = bigInt("FF", 16);
var fiftyFiveGoogol = bigInt("<55>0", googol);

Note that Javascript numbers larger than 9007199254740992 and smaller than -9007199254740992 are not precisely represented numbers and will not produce exact results. If you are dealing with numbers outside that range, it is better to pass in strings.

Method Chaining

Note that bigInt operations return bigInts, which allows you to chain methods, for example:

var salary = bigInt(dollarsPerHour).times(hoursWorked).plus(randomBonuses)

Constants

There are three constants already stored that you do not have to construct with the bigInt function yourself:

• bigInt.one, equivalent to bigInt(1)
• bigInt.zero, equivalent to bigInt(0)
• bigInt.minusOne, equivalent to bigInt(-1)

Methods

abs()

Returns the absolute value of a bigInt.

• bigInt(-45).abs() => 45
• bigInt(45).abs() => 45

add(number)

Performs addition.

• bigInt(5).add(7) => 12

and(number)

Performs the bitwise AND operation.

• bigInt(6).and(3) => 2

compare(number)

Performs a comparison between two numbers. If the numbers are equal, it returns 0. If the first number is greater, it returns 1. If the first number is lesser, it returns -1.

• bigInt(5).compare(5) => 0
• bigInt(5).compare(4) => 1
• bigInt(4).compare(5) => -1

compareAbs(number)

Performs a comparison between the absolute value of two numbers.

• bigInt(5).compareAbs(-5) => 0
• bigInt(5).compareAbs(4) => 1
• bigInt(4).compareAbs(-5) => -1

compareTo(number)

Alias for the compare method.

divide(number)

Performs integer division, disregarding the remainder.

• bigInt(59).divide(5) => 11

divmod(number)

Performs division and returns an object with two properties: quotient and remainder. The sign of the remainder will match the sign of the dividend.

• bigInt(59).divmod(5) => {quotient: bigInt(11), remainder: bigInt(4) }
• bigInt(-5).divmod(2) => {quotient: bigInt(-2), remainder: bigInt(-1) }

eq(number)

Alias for the equals method.

equals(number)

Checks if two numbers are equal.

• bigInt(5).equals(5) => true
• bigInt(4).equals(7) => false

gcd(a, b)

Finds the greatest common denominator of a and b.

• bigInt.gcd(42,56) => 14

geq(number)

Alias for the greaterOrEquals method.

greater(number)

Checks if the first number is greater than the second.

• bigInt(5).greater(6) => false
• bigInt(5).greater(5) => false
• bigInt(5).greater(4) => true

greaterOrEquals(number)

Checks if the first number is greater than or equal to the second.

• bigInt(5).greaterOrEquals(6) => false
• bigInt(5).greaterOrEquals(5) => true
• bigInt(5).greaterOrEquals(4) => true

gt(number)

Alias for the greater method.

isDivisibleBy(number)

Returns true if the first number is divisible by the second number, false otherwise.

• bigInt(999).isDivisibleBy(333) => true
• bigInt(99).isDivisibleBy(5) => false

isEven()

Returns true if the number is even, false otherwise.

• bigInt(6).isEven() => true
• bigInt(3).isEven() => false

isNegative()

Returns true if the number is negative, false otherwise. Returns false for 0 and true for -0.

• bigInt(-23).isNegative() => true
• bigInt(50).isNegative() => false

isOdd()

Returns true if the number is odd, false otherwise.

• bigInt(13).isOdd() => true
• bigInt(40).isOdd() => false

isPrime()

Returns true if the number is prime, false otherwise.

• bigInt(5).isPrime() => true
• bigInt(6).isPrime() => false

isPositive()

Return true if the number is positive, false otherwise. Returns true for 0 and false for -0.

• bigInt(54).isPositive() => true
• bigInt(-1).isPositive() => false

isUnit()

Return true if the number is 1 or -1, false otherwise.

• bigInt.one.isUnit() => true
• bigInt.minusOne.isUnit() => true
• bigInt(5).isUnit() => false

lcm(a,b)

Finds the least common multiple of a and b.

• bigInt.lcm(21, 6) => 42

leq(number)

Alias for the lesserOrEquals method.

lesser(number)

Checks if the first number is lesser than the second.

• bigInt(5).lesser(6) => true
• bigInt(5).lesser(5) => false
• bigInt(5).lesser(4) => false

lesserOrEquals(number)

Checks if the first number is less than or equal to the second.

• bigInt(5).lesserOrEquals(6) => true
• bigInt(5).lesserOrEquals(5) => true
• bigInt(5).lesserOrEquals(4) => false

lt(number)

Alias for the lesser method.

max(a,b)

Returns the largest of a and b.

• bigInt.max(77, 432) => 432

min(a,b)

Returns the smallest of a and b.

• bigInt.min(77, 432) => 77

minus(number)

Alias for the subtract method.

• bigInt(3).minus(5) => -2

mod(number)

Performs division and returns the remainder, disregarding the quotient. The sign of the remainder will match the sign of the dividend.

• bigInt(59).mod(5) => 4
• bigInt(-5).mod(2) => -1

modPow(exp, mod)

Takes the number to the power exp modulo mod.

• bigInt(10).modPow(3, 30) => 10

multiply(number)

Performs multiplication.

• bigInt(111).multiply(111) => 12321

neq(number)

Alias for the notEquals method.

next()

Adds one to the number.

• bigInt(6).next() => 7

not()

Performs the bitwise NOT operation.

• bigInt(10).not() => -5

notEquals(number)

Checks if two numbers are not equal.

• bigInt(5).notEquals(5) => false

• bigInt(4).notEquals(7) => true

• bigInt(6).next() => 7

or(number)

Performs the bitwise OR operation.

• bigInt(13).or(10) => 15

over(number)

Alias for the divide method.

• bigInt(59).over(5) => 11

plus(number)

Alias for the add method.

• bigInt(5).plus(7) => 12

pow(number)

Performs exponentiation. If the exponent is less than 0, pow returns 0. bigInt.zero.pow(0) returns 1.

• bigInt(16).pow(16) => 18446744073709551616

prev(number)

Subtracts one from the number.

• bigInt(6).prev() => 5

randBetween(min, max)

Returns a random number between min and max.

• bigInt.randBetween("-1e100", "1e100") => (for example) 8494907165436643479673097939554427056789510374838494147955756275846226209006506706784609314471378745

remainder(number)

Alias for the mod method.

shiftLeft(n)

Shifts the number left by n places in its binary representation. If a negative number is provided, it will shift right.

• bigInt(8).shiftLeft(2) => 32
• bigInt(8).shiftLeft(-2) => 2

shiftRight(n)

Shifts the number right by n places in its binary representation. If a negative number is provided, it will shift left.

• bigInt(8).shiftRight(2) => 2
• bigInt(8).shiftRight(-2) => 32

square()

Squares the number

• bigInt(3).square() => 9

subtract(number)

Performs subtraction.

• bigInt(3).subtract(5) => -2

times(number)

Alias for the multiply method.

• bigInt(111).times(111) => 12321

toJSNumber()

Converts a bigInt into a native Javascript number. Loses precision for numbers outside the range [-9007199254740992, 9007199254740992].

• bigInt("18446744073709551616").toJSNumber() => 18446744073709552000

xor(number)

Performs the bitwise XOR operation.

• bigInt(12).xor(5) => 9

Override Methods

toString(radix = 10)

Converts a bigInt to a string. There is an optional radix parameter (which defaults to 10) that converts the number to the given radix. Digits in the range 10-36 will use the letters a-z.

• bigInt("1e9").toString() => "1000000000"
• bigInt("1e9").toString(16) => "3b9aca00"

Bases larger than 36 are supported. If a digit is larger than 36, it will be enclosed in angle brackets.

• bigInt(567890).toString(100) => "<56><78><90>"

Negative bases are also supported.

• bigInt(12345).toString(-10) => "28465"

Base 1 and base -1 are also supported.

• bigInt(-15).toString(1) => "-111111111111111"
• bigInt(-15).toString(-1) => "101010101010101010101010101010"

Base 0 is only allowed for the number zero.

• bigInt(0).toString(0) => 0
• bigInt(1).toString(0) => Error: Cannot convert nonzero numbers to base 0.

valueOf()

Converts a bigInt to a native Javascript number. This override allows you to use native arithmetic operators without explicit conversion:

• bigInt("100") + bigInt("200") === 300; //true