#
BigNumber

Explain about BigNumber here...

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Importing

/////
// CommonJS:
// From the Umbrella ethers package...
const { BigNumber } = require("ethers");
// From the bignumber pacakge...
const { BigNumber } = require("@ethersproject/bignumber");
/////
// ES6 and TypeScript:
// From the Umbrella ethers package...
import { BigNumber } from "ethers";
// From the bignumber pacakge...
import { BigNumber } from "@ethersproject/bignumber";

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Types

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BigNumberish

Many functions and methods in this library take in values which can be non-ambiguously and safely converted to a BigNumber. These values can be sepcified as:

string

A hexstring or a decimal string, either of which may be negative.

BytesLike

A BytesLike Object, such as an Array or Uint8Array.

BigNumber

An existing BigNumber instance.

number

A number that is within the safe range for JavaScript numbers.

BigInt

A JavaScript BigInt object, on environments that support BigInt.

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Creating Instances

The constructor of BigNumber cannot be called directly. Instead, Use the static `BigNumber.from`.

BigNumber . from ( aBigNumberish ) ⇒ BigNumber

Returns an instance of a BigNumber for aBigNumberish.

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Examples:

Skipping JavaScript Evaluation.

##
Methods

The BigNumber class is immutable, so no operations can change the value it represents.

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Math Operations

bignumber . add ( otherValue ) ⇒ BigNumber

Returns a BigNumber with the value of bignumber + otherValue.

bignumber . sub ( otherValue ) ⇒ BigNumber

Returns a BigNumber with the value of bignumber – otherValue.

bignumber . mul ( otherValue ) ⇒ BigNumber

Returns a BigNumber with the value of bignumber × otherValue.

bignumber . div ( divisor ) ⇒ BigNumber

Returns a BigNumber with the value of bignumber ÷ divisor.

bignumber . mod ( divisor ) ⇒ BigNumber

Returns a BigNumber with the value of the remainder of bignumber ÷ divisor.

bignumber . pow ( exponent ) ⇒ BigNumber

Returns a BigNumber with the value of bignumber to the power of exponent.

bignumber . abs ( ) ⇒ BigNumber

Returns a BigNumber with the absolute value of bignumber.

bignumber . maskn ( bitcount ) ⇒ BigNumber

Returns a BigNumber with the value of bignumber with bits beyond the bitcount least significant bits set to zero.

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Two's Compliment

Two's Complicment is an elegant method used to encode and decode fixed-width signed values while efficiently preserving mathematic operations. Most users will not need to interact with these.

bignumber . fromTwos ( bitwidth ) ⇒ BigNumber

Returns a BigNumber with the value of bignumber converted from twos-compliment with bitwidth.

bignumber . toTwos ( bitwidth ) ⇒ BigNumber

Returns a BigNumber with the value of bignumber converted to twos-compliment with bitwidth.

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Comparison and Equivalence

bignumber . eq ( otherValue ) ⇒ boolean

Returns true if and only if the value of bignumber is equal to otherValue.

bignumber . lt ( otherValue ) ⇒ boolean

Returns true if and only if the value of bignumber < otherValue.

bignumber . lte ( otherValue ) ⇒ boolean

Returns true if and only if the value of bignumber ≤ otherValue.

bignumber . gt ( otherValue ) ⇒ boolean

Returns true if and only if the value of bignumber > otherValue.

bignumber . gte ( otherValue ) ⇒ boolean

Returns true if and only if the value of bignumber ≥ otherValue.

bignumber . isZero ( ) ⇒ boolean

Returns true if and only if the value of bignumber is zero.

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Conversion

bignumber . toNumber ( ) ⇒ number

Returns the value of bignumber as a JavaScript value.

This will throw an error if the value is greater than or equal to Number.MAX_SAFE_INTEGER or less than or equal to Number.MIN_SAFE_INTEGER.

bignumber . toString ( ) ⇒ string

Returns the value of bignumber as a base-10 string.

bignumber . toHexString ( ) ⇒ string

Returns the value of bignumber as a base-16, `0x`-prefixed hexstring.

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Inspection

BigNumnber . isBigNumber ( object ) ⇒ boolean

Returns true if and only if the object is a BigNumber object.

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Examples

Skipping JavaScript Evaluation.

##
Notes

A few short notes on numbers...

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Why can't I just use numbers?

The first problem many encounter when dealing with Ethereum is the concept of numbers. Most common currencies are broken down with very little granularity. For example, there are only 100 cents in a single dollar. However, there are 1018 wei in a single ether.

JavaScript uses IEEE 754 double-precision binary floating point numbers to represent numeric values. As a result, there are holes in the integer set after 9,007,199,254,740,991; which is problematic for Ethereum// because that is only around 0.009 ether (in wei), which means any value over that will begin to experience rounding errors.

To demonstrate how this may be an issue in your code, consider:

Skipping JavaScript Evaluation.

To remedy this, all numbers (which can be large) are stored and manipulated as Big Numbers.

The functions parseEther( etherString ) and formatEther( wei ) can be used to convert between string representations, which are displayed to or entered by the user and Big Number representations which can have mathematical operations handled safely.

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