BigInt.asIntN()
BigInt.asIntN 静态方法将 BigInt 值转换为一个 -2^(width-1) 与 2^(width-1)-1 之间的有符号整数。
尝试一下
const I64_CEIL = 2n ** 63n;
console.log(BigInt.asIntN(64, I64_CEIL - 1n));
// 9223372036854775807n (2n ** 64n - 1n, the maximum non-wrapping value)
console.log(BigInt.asIntN(64, I64_CEIL));
// -9223372036854775808n (wraps to min value)
console.log(BigInt.asIntN(64, I64_CEIL + 1n));
// -9223372036854775807n (min value + 1n)
console.log(BigInt.asIntN(64, I64_CEIL * 2n));
// 0n (wrapped around to zero)
console.log(BigInt.asIntN(64, -I64_CEIL * -42n));
// 0n (also wraps on negative multiples)
语法
BigInt.asIntN(width, bigint);
参数
返回值
bigint 模 (modulo) 2^width 作为有符号整数的值。
示例
保持在 64 位范围内
BigInt.asIntN() 方法对于保持在 64 位 (64-bit) 算数范围内非常有用。
js
const max = 2n ** (64n - 1n) - 1n;
BigInt.asIntN(64, max);
// ↪ 9223372036854775807n
BigInt.asIntN(64, max + 1n);
// ↪ -9223372036854775808n
// negative because of overflow
规范
| 规范 |
|---|
| ECMAScript® 2027 Language Specification # sec-bigint.asintn |