JavaScript Bigint

The bigint is a new primitive data type in JavaScript. It was introduced in ES11 version of JavaScript. it represents the whole number. It can hold numbers larger than 253 – 1. The BigInt uses the arbitrary-precision arithmetic. This article covers how to use bigInt, the arithmetic operations allowed, how to convert bigint to number and number to bigint, etc.

Defining bigint

There are two ways in which you create bigint.

A bigInt is created by appending n to the end of an integer literal

let big1 = 9007199254740991n;
console.log(typeof(big1))


//******output***
//bigint

You can even use binary, octal or hexadecimal notation. Just use n at the end. Legacy octal syntax (0640) is not allowed, only new-style (0o064n).

let bigHex = 0xffffffffffffffn  
console.log(bigHex);          //72057594037927935n

const bigBin = 0b11111111111111111111111111111111111111111111111111111n
console.log(bigBin)          //9007199254740991n

const bigOct = 0o24045162451214n
console.log(bigOct)          //1379385627276n

or by calling the function Global function BigInt()

let big2 = BigInt(9007199254099);
console.log(typeof(big2))


//******output***
//bigint
let bigNum= BigInt("9045141578140991");
console.log(bigNum)        //9045141578140991n  

Hex, binary & octal numbers.

let bigHex = BigInt("0xffffffffffffff");  
console.log(bigHex);          //72057594037927935n

const bigBin = BigInt("0b11111111111111111111111111111111111111111111111111111");    
console.log(bigBin)          //9007199254740991n

const bigOct = BigInt("0o24045162451214n")
console.log(bigOct)          //1379385627276n

Max Value

The bigint can handle the large values and not limited as the Number datatype, which has (Number.MAX_SAFE_INTEGER). BigInt is limited by the available memory of the host system

Arithmetic Operations

The BigInt can be used with the following arithmetic operations +*-**%. Bitwise operators like &, | , ^ , ~, << , >>, (except >>> Zero fill right shift) operators.

The unary operator + is not supported. Also >>> is not supported, as all BigInts are signed

let bigVar=9007199254740991n;

let b=bigVar+1n;
console.log(b);      //9007199254740992n

b=bigVar*10n;
console.log(b);     //90071992547409910n

b=bigVar/5n;
console.log(b);     //1801439850948198n

The / division operator rounds of the final result to the whole number. For example, dividing 5/2 results in 2 and not 2.5. i.e it is an integer and not decimal.

console.log(4n / 2n);    //2n
console.log(5n / 2n);    //2n  and not 2.5 

bigint can not be mixed with operations where numbers are involved as shown below. Either you convert number to bigint or convert bigint to number.

let numVar=100;
let bigVar= 100n;

console.log(numVar+bigVar);

*** Error *****
Cannot mix BigInt and other types, use explicit conversions

Convert Number to BigInt

You can use the BigInt function to convert the number to a bigInt

let numVar= 100;
let bigVar=BigInt(numVar)
console.log(bigVar)
console.log(typeof(bigVar))

//**output
//100n
//bigint

Convert BigInt to Number

You can convert the bigInt to number by using the Number function. Beware of the fact that you may lose precision when you coerce bigint to number.

let bigVar= 100n;
let numVar=Number(bigVar)
console.log(numVar)
console.log(typeof(numVar))

//**output
//100
//number

Comparison operators

The comparison operators work well between bigInt and a number

console.log(1n < 2)     //true
console.log(2n > 1)     //true
console.log(2n > 2)     //false
console.log(2n >= 2)    //true

BigInt 0 is loosely equal (0n==0 is true) to number 0.  But is not strictly equal to a Number (0n===0 is false)

console.log(0n === 0)   // false
console.log(0n == 0)    // true

Conditionals

BigInt behaves like a Number when converted to Boolean.

Boolean(0n)
      // false

Boolean(12n)
     // true

Summary

The bigint is a primitive type. It is added so as to support the large number. bigint cannot be used in the operations involving numbers. They must be coerced to do that. Beware of the fact that you may lose precision when you coerce bigint to number and back. You can make use of comparison operators to compare bigInt with a number.

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