bitLength property

int bitLength

Returns the minimum number of bits required to store this big integer.

The number of bits excludes the sign bit, which gives the natural length for non-negative (unsigned) values. Negative values are complemented to return the bit position of the first bit that differs from the sign bit.

To find the number of bits needed to store the value as a signed value, add one, i.e. use x.bitLength + 1.

x.bitLength == (-x-1).bitLength

new BigInt.from(3).bitLength == 2;   // 00000011
new BigInt.from(2).bitLength == 2;   // 00000010
new BigInt.from(1).bitLength == 1;   // 00000001
new BigInt.from(0).bitLength == 0;   // 00000000
new BigInt.from(-1).bitLength == 0;  // 11111111
new BigInt.from(-2).bitLength == 1;  // 11111110
new BigInt.from(-3).bitLength == 2;  // 11111101
new BigInt.from(-4).bitLength == 2;  // 11111100

Implementation 

int get bitLength;