Simple function for adding an arbitrary number of bits

add-bits.js

/** addBits(A, B, S?)
 * @param A The first set of bits
 { BigInt | Number | String === /^[01]*$/ | Object == Array }
 * @param B The second set of bits
 { BigInt | Number | String === /^[01]*$/ | Object == Array }
 * @param S The signature boolean
 = true -> Use signed mode (int)
 = false -> Use unsigned mode (uint)
 * @return String === /^[01]+$/
 */

function addBits(A, B, S = false) {
    let O = [];

    if(typeof A == 'number')
        A = A.toString(2);
    if(typeof A == 'string')
        A = A.split('');
    if(typeof A == 'object' && A.map)
        A = A.map(x => parseInt(x));

    if(typeof B == 'number')
        B = B.toString(2);
    if(typeof B == 'string')
        B = B.split('');
    if(typeof B == 'object' && B.map)
        B = B.map(x => parseInt(x));

    A = A.reverse();
    B = B.reverse();

    let c = 0;
    for(let i = 0, l = Math.max(A.length, B.length); i < l; i++) {
        let a = A[i] | 0,
            b = B[i] | 0;

        console.log({ a, b, c, i });

        if(!i) {
            c = a & b;

            O.push(a ^ b);
        } else {
            O.push((a ^ b) ^ c);

            c = (a & b) | (a & c);
        }
    }

    if(S)
        O.push(c);

    return O.reverse().join('');
}