if (TSP1 < player1) {
    $("#errornotice").html("Minimum TSP player 1 " is " + player1);
    player1-list.focus();
} else if (TSP2 < player2) {
    $("#errornotice").html("Minimum TSP player 2 " is " + player2);
    player2-list.focus();
} else if (TSP3 < player3) {
    $("#errornotice").html("Minimum TSP player 3 " is " + player3);
    player3-list.focus();
} else if (TSP4 < player4) {
    $("#errornotice").html("Minimum TSP player 4 " is " + player4);
    player4-list.focus();
}

<b><span style="color:red" id ="errornotice"></span></b><br>

for (var a = 1; a < 4; a++){
     if (thuisTSP+a < speler+a) {
          $("#errornotice").html("Minimum TSP player" +a+ " is " + player+a);
          Thuisspeler1-list+a.focus();
      }
}