Credit card validation using Luhn algorithm or mod 10 algorithm

The Luhn algorithm, also known as the modulus 10 or mod 10 algorithm, is a simple checksum formula used to validate a variety of identification numbers, such as credit card numbers, IMEI numbers, Canadian Social Insurance Numbers

function check(cardno){

let nDigit=cardno.length;
let sum=0;
let isSecond=false;

for(let i=nDigit-1;i>=0;i--){
let d=Number(cardno[i]);
    if(isSecond){
        d=d*2
    }

    sum+=parseInt(d/10);
    sum+=d%10;

    isSecond=!isSecond;
}

if(sum%10==0){
    return true;
}
else{
    return false
}

}

if(check(79927398713)){
    console.log("This is a Valid Card");
}
else{
    console.log("This is not a  Valid Card");
}