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BigInt.asUintN()

The BigInt.asUintN static method clamps a BigInt value to the given number of bits, and returns that value as an unsigned integer.

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Syntax

BigInt.asUintN(bits, bigint);

Parameters

bits

The amount of bits available for the integer size.

bigint

The BigInt value to clamp to fit into the supplied bits.

Returns

The value of bigint modulo 2^bits, as an unsigned integer.

Description

The BigInt.asUintN method clamps a BigInt value to the given number of bits, and interprets the result as an unsigned integer. Unsigned integers have no sign bits and are always non-negative. For example, for BigInt.asUintN(4, 25n), the value 25n is clamped to 9n:

25n = 00011001 (base 2)
         ^==== Clamp to four remaining bits
===>      1001 (base 2) = 9n

Note: BigInt values are always encoded as two's complement in binary.

Examples

Staying in 64-bit ranges

The BigInt.asUintN() method can be useful to stay in the range of 64-bit arithmetic.

const max = 2n ** 64n - 1n;

BigInt.asUintN(64, max);
// ↪ 18446744073709551615n

BigInt.asUintN(64, max + 1n);
// ↪ 0n
// zero because of overflow: the lowest 64 bits are all zeros

Specifications

Browser compatibility

Desktop Mobile Server
Chrome Edge Firefox Internet Explorer Opera Safari WebView Android Chrome Android Firefox for Android Opera Android Safari on IOS Samsung Internet Deno Node.js
asUintN
67
79
68
No
54
14
67
67
68
48
14
9.0
1.0
10.4.0

See also

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Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/BigInt/asUintN