CARD NUMBER VALIDATION

JavaScript

function checkCard (num) {

    var arr = num.replace(/ /gi,'').split('').reverse();
    
    function sumDigits (n) {
        return (n % 10) + 1;
    }
    
    var doubled = arr.map(function(d, i) {
        if (i % 2 !== 0) {
            var t = +d * 2;
            return t >= 10 ? sumDigits(t) : t;        
        } else {
            return +d;
        }
    });
    
    var result = doubled.reduce(function (a,b) { return a + b;});
    
    return result % 10 === 0 ? 1 : 0;
    
}

console.log(checkCard("6370 1675 9034 6211 774"));