function hitungNomorBit(angka, nomorBit) {
    if (nomorBit !== 0 && nomorBit !== 1) {
        return null;
    }
 
    if (angka === 0) {
        if (nomorBit === 0) return 1;
        else return 0;
    }
 
    let jumlahKemunculan = 0;
    let sisaBagi;
 
    while (angka > 0) {
        sisaBagi = angka % 2;
 
        if (sisaBagi === nomorBit) {
            jumlahKemunculan++;
        }
 
        angka = (angka - sisaBagi) / 2;
    }
 
    return jumlahKemunculan;
}
 
// pengujian
console.log(hitungNomorBit(13, 0)); 
console.log(hitungNomorBit(13, 1)); 
console.log(hitungNomorBit(13, 2)); 
 
 

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