long.js

A Long class for representing a 64 bit two's-complement integer value derived from the Closure Library for stand-alone use and extended with unsigned support.

Background

As of ECMA-262 5th Edition, "all the positive and negative integers whose magnitude is no greater than 253 are representable in the Number type", which is "representing the doubleprecision 64-bit format IEEE 754 values as specified in the IEEE Standard for Binary Floating-Point Arithmetic". The maximum safe integer in JavaScript is 253-1.

Example: 264-1 is 18446744073709551615 but in JavaScript it evaluates to 18446744073709552000.

Furthermore, bitwise operators in JavaScript "deal only with integers in the range −231 through 231−1, inclusive, or in the range 0 through 232−1, inclusive. These operators accept any value of the Number type but first convert each such value to one of 232 integer values."

In some use cases, however, it is required to be able to reliably work with and perform bitwise operations on the full 64 bits. This is where long.js comes into play.

Usage

The class is compatible with CommonJS and AMD loaders and is exposed globally as Long if neither is available.

var Long = require("long");

var longVal = new Long(0xFFFFFFFF, 0x7FFFFFFF);

console.log(longVal.toString());
...

API

Constructor

• new Long(low: number, high: number, unsigned?: boolean) Constructs a 64 bit two's-complement integer, given its low and high 32 bit values as signed integers. See the from* functions below for more convenient ways of constructing Longs.

Fields

• Long#low: number The low 32 bits as a signed value.

• Long#high: number The high 32 bits as a signed value.

• Long#unsigned: boolean Whether unsigned or not.

Constants

• Long.ZERO: Long Signed zero.

• Long.ONE: Long Signed one.

• Long.NEG_ONE: Long Signed negative one.

• Long.UZERO: Long Unsigned zero.

• Long.UONE: Long Unsigned one.

• Long.MAX_VALUE: Long Maximum signed value.

• Long.MIN_VALUE: Long Minimum signed value.

• Long.MAX_UNSIGNED_VALUE: Long Maximum unsigned value.

Utility

• Long.isLong(obj: *): boolean Tests if the specified object is a Long.

• Long.fromBits(lowBits: number, highBits: number, unsigned?: boolean): Long Returns a Long representing the 64 bit integer that comes by concatenating the given low and high bits. Each is assumed to use 32 bits.

• Long.fromBytes(bytes: number[], unsigned?: boolean, le?: boolean): Long Creates a Long from its byte representation.

• Long.fromBytesLE(bytes: number[], unsigned?: boolean): Long Creates a Long from its little endian byte representation.

• Long.fromBytesBE(bytes: number[], unsigned?: boolean): Long Creates a Long from its big endian byte representation.

• Long.fromInt(value: number, unsigned?: boolean): Long Returns a Long representing the given 32 bit integer value.

• Long.fromNumber(value: number, unsigned?: boolean): Long Returns a Long representing the given value, provided that it is a finite number. Otherwise, zero is returned.

• Long.fromString(str: string, unsigned?: boolean, radix?: number) Long.fromString(str: string, radix: number) Returns a Long representation of the given string, written using the specified radix.

• Long.fromValue(val: *, unsigned?: boolean): Long Converts the specified value to a Long using the appropriate from* function for its type.

Methods

• Long#add(addend: Long | number | string): Long Returns the sum of this and the specified Long.

• Long#and(other: Long | number | string): Long Returns the bitwise AND of this Long and the specified.

• Long#compare/comp(other: Long | number | string): number Compares this Long's value with the specified's. Returns 0 if they are the same, 1 if the this is greater and -1 if the given one is greater.

• Long#divide/div(divisor: Long | number | string): Long Returns this Long divided by the specified.

• Long#equals/eq(other: Long | number | string): boolean Tests if this Long's value equals the specified's.

• Long#getHighBits(): number Gets the high 32 bits as a signed integer.

• Long#getHighBitsUnsigned(): number Gets the high 32 bits as an unsigned integer.

• Long#getLowBits(): number Gets the low 32 bits as a signed integer.

• Long#getLowBitsUnsigned(): number Gets the low 32 bits as an unsigned integer.

• Long#getNumBitsAbs(): number Gets the number of bits needed to represent the absolute value of this Long.

• Long#greaterThan/gt(other: Long | number | string): boolean Tests if this Long's value is greater than the specified's.

• Long#greaterThanOrEqual/gte/ge(other: Long | number | string): boolean Tests if this Long's value is greater than or equal the specified's.

• Long#isEven(): boolean Tests if this Long's value is even.

• Long#isNegative(): boolean Tests if this Long's value is negative.

• Long#isOdd(): boolean Tests if this Long's value is odd.

• Long#isPositive(): boolean Tests if this Long's value is positive.

• Long#isZero/eqz(): boolean Tests if this Long's value equals zero.

• Long#lessThan/lt(other: Long | number | string): boolean Tests if this Long's value is less than the specified's.

• Long#lessThanOrEqual/lte/le(other: Long | number | string): boolean Tests if this Long's value is less than or equal the specified's.

• Long#modulo/mod/rem(divisor: Long | number | string): Long Returns this Long modulo the specified.

• Long#multiply/mul(multiplier: Long | number | string): Long Returns the product of this and the specified Long.

• Long#negate/neg(): Long Negates this Long's value.

• Long#not(): Long Returns the bitwise NOT of this Long.

• Long#notEquals/neq/ne(other: Long | number | string): boolean Tests if this Long's value differs from the specified's.

• Long#or(other: Long | number | string): Long Returns the bitwise OR of this Long and the specified.

• Long#shiftLeft/shl(numBits: Long | number | string): Long Returns this Long with bits shifted to the left by the given amount.

• Long#shiftRight/shr(numBits: Long | number | string): Long Returns this Long with bits arithmetically shifted to the right by the given amount.

• Long#shiftRightUnsigned/shru/shr_u(numBits: Long | number | string): Long Returns this Long with bits logically shifted to the right by the given amount.

• Long#rotateLeft/rotl(numBits: Long | number | string): Long Returns this Long with bits rotated to the left by the given amount.

• Long#rotateRight/rotr(numBits: Long | number | string): Long Returns this Long with bits rotated to the right by the given amount.

• Long#subtract/sub(subtrahend: Long | number | string): Long Returns the difference of this and the specified Long.

• Long#toBytes(le?: boolean): number[] Converts this Long to its byte representation.

• Long#toBytesLE(): number[] Converts this Long to its little endian byte representation.

• Long#toBytesBE(): number[] Converts this Long to its big endian byte representation.

• Long#toInt(): number Converts the Long to a 32 bit integer, assuming it is a 32 bit integer.

• Long#toNumber(): number Converts the Long to a the nearest floating-point representation of this value (double, 53 bit mantissa).

• Long#toSigned(): Long Converts this Long to signed.

• Long#toString(radix?: number): string Converts the Long to a string written in the specified radix.

• Long#toUnsigned(): Long Converts this Long to unsigned.

• Long#xor(other: Long | number | string): Long Returns the bitwise XOR of this Long and the given one.

WebAssembly support

WebAssembly supports 64-bit integer arithmetic out of the box, hence a tiny WebAssembly module is used to compute operations like multiplication, division and remainder more efficiently (slow operations like division are around twice as fast), falling back to floating point based computations in JavaScript where WebAssembly is not yet supported, e.g., in older versions of node.

Building

To build an UMD bundle to dist/long.js, run:

$> npm install
$> npm run build

Running the tests:

$> npm test