Credit Card

function isValid(ccnum){
    var sum = 0;
  ccnum = ccnum.split('');
  for(var i=0; i < ccnum.length; i++){
      if(ccnum[i] == ' '){
          ccnum.splice(i,1);
      }
  }
  for(var t = 0; t < ccnum.length; t=t+2){
        ccnum[t] == ccnum[t]*2;
  }
  for(var w = 0; w < ccnum.length; w++){
      sum = sum + Number(ccnum[w]); 
  }
    if(sum % 10 === 0){
        return true;
    }else{
        return false;
    }

}

console.log(isValid("4408 0412 3456 7893") === false)
console.log(isValid("5000000000000000") === false)