sha512 leading zeros bis

crypto=require('crypto');

for (var i=0; true; i++) {
  var myhash=crypto.createHash('sha256').update(""+i+"5748211839773").digest('hex');
  if (myhash[0]==0 && myhash[1]==0 && myhash[2]==0 && myhash[3]==0 && myhash[4]==0 && myhash[5]==0) {
    console.log(i);
    break;
  };
};