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What is a BigInt in JavaScript?
BigInt
BigInt is a built-in object that provides a way to store numbers larger than Number.MAX_SAFE_INTEGER.
Take a look at the example below to see why BigInt is needed.
var maxIntNum = 9007199254740991;
var largeNumber = maxIntNum + 2; // 9007199254740992
The expected result for the above operation is 9007199254740993, but we get 9007199254740992. The reason is that JavaScript uses 64-bits to store a number, so once we try to create a number larger than this, it can’t be stored.
To solve this problem, we can use a BigInt.
Creating a BigInt
We can create a BigInt in two ways:
- Adding
nto the end of the number. - Using the BigInt constructor.
// add n to end of the number to create a BigIntvar num = 100000000000000000n;num + 10n; // 100000000000000010n// creating BigInt from hexadecimal literal - append n at the endvar num = 0x1fffffffffffffnnum; // 9007199254740991n// using BigInt constuctorvar num = BigInt(100000000000000000);num+10n; //100000000000000010nvar fromHex = BigInt('0x1fffffffffffff');fromHex; // 9007199254740991n
Checking if a number is a BigInt
typeof will return bigint for BigInt numbers.
var num = 100000000000000000n;typeof num; // bigintvar num2 = BigInt(100000000000000000);typeof num2; // bigint
Creating an Object from a BigInt
We can create an object from a BigInt value, the type of which will be object.
var bigIntAsObject = Object(1n);bigIntAsObject; // BigInt {1n}typeof bigIntAsObject; // "object"
Remember, we cannot mix normal numbers with BigInts. If we try to, it will result in an error.
num + 10;
// Uncaught TypeError: Cannot mix BigInt and other types, use explicit conversions
To solve this, we can convert our normal number to a BigInt with the following.
num + BigInt(10);
Arithmetic operations with BigInt
Arithmetic operation on BigInt is mostly like arithmetic operation on regular numbers. However, when we perform division, the fractional part in the result is removed.
var num = BigInt(10);// Additionnum + 10n; // 20n// Subtractionnum - BigInt(5); // 15n// Multiplicationnum * 10n; // 150n// Exponent operatornum ** 10n; // 10000000000n// DIVISION// when we perform division , the fractional part in the result is removedvar n = 5n;n / 2n; // 2n// MODULOvar n = 5n;n % 2n; // 1n
Equality comparison
When BigInt is compared with non-BigInt numbers, will perform type conversion and check, using == but strict-equality === type conversion is not performed and returns false if values and types are not matched.
10n == 10; // true
10n === 10; // false
Relational operations
These are similar to numerical comparisons.
1n < 2n // true2n > 1n // true2 > 2n // false2n > 2n // false2n >= 2n // true
Converting to a Boolean
BigInts behave like numbers when converting to booleans or checking for true or false values.
Boolean(0n) // false
Boolean(12n) // true
!0n; // true
!12n; // false.
toString
The toString method will return a string representing the specified BigInt object without n at the end of the number.
var a = 10n;
a.toString(); //10
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