即使不满足条件，while循环的结果仍然会发生

Question

I'm practising writing Javascript by making a Roguelike dungeon game but there is a problem when I want to create monsters. I have written a while loop such as:

this.getRandomCoordinatesInRoom = function(roomNumber) {
var validLocationFound = false;

while (!validLocationFound){
  // Generate co-ords in room first
  x = Math.floor(Math.random() * (this.roomList[roomNumber].width) + (this.roomList[roomNumber].posX));
  y = Math.floor(Math.random() * (this.roomList[roomNumber].height) + (this.roomList[roomNumber].posY));

  // Find location of (x,y) in Dungeon Array

  //alert(arrayLocation);
  var tmpX = ((this.roomList[roomNumber]).posX + x);
  var tmpY = ((this.roomList[roomNumber]).posY + y);
  var arrayLocation = ((tmpY * 80) + tmpX);
  //var arrayLocation = ((this.roomList[roomNumber].posX + x) + (80 * (this.roomList[roomNumber].posY + y)));
  if (this.dungeonArray[(tmpY + tmpX)] === "floor") {
    validLocationFound = true;
  };

  if ((x<this.roomList[roomNumber].posX) || (x>(this.roomList[roomNumber].posX + this.roomList[roomNumber].width))){
    alert("x out of bounds");
  };

  if ((y<this.roomList[roomNumber].posY) || (y>(this.roomList[roomNumber].posY + this.roomList[roomNumber].height))){
    alert("y out of bounds");
  };
  writeToScreen("Room upper left corner = " + (this.roomList[roomNumber].posX).toString() + "," + (this.roomList[roomNumber].posY).toString(),10);
  return [x,y];

  if (!(getTileAt(arrayLocation) === "floor")){
    alert("It messed up");
  }
};

The code randomly generates an x,y coordinate and converts it to a single number (My dungeon array is one dimensional, 0-79 across and then 80 is a new row). however, even when the code generates a coordinate that isn't valid (!= "floor"), it still finishes the function as though it returned true. Why is this?

Answer 1

Your function returns [x,y] from inside the while loop. Declare the variables outside of the loop and then return the value from outside the loop. Or else, return is when validLocationFound is true.

var x, y ;
while(...) {
    ...
}
return [x, y];