NodeJS MySQL - 检查colum是否存在

Question

在普通的java中，很容易检查colum是否与@Override public boolean onTouchEvent(MotionEvent event) { int x = (int)(event.getX()/tileSize); int y = (int)(event.getY()/tileSize); switch (event.getAction()) { case MotionEvent.ACTION_DOWN: map[x][y] = true; break; case MotionEvent.ACTION_MOVE: case MotionEvent.ACTION_UP: } return false; } 一起存在但是你如何在javascript中这样做

  private void init(){
  tileSize = 10;

  paint1 = new Paint();
  paint1.setColor(Color.BLUE);
  paint1.setStrokeWidth(10);
  paint1.setStyle(Paint.Style.STROKE);

  paint2 = new Paint();
  paint2.setColor(Color.RED);
  paint2.setStrokeWidth(10);
  paint2.setStyle(Paint.Style.STROKE);

 }

 @Override
 protected void onDraw(Canvas canvas) {
  super.onDraw(canvas);
for (int i = 0; i < x; i++){
    for (int j = 0; j < y; j++){
        Paint p = null; 
        if(map[i][j]){
        p=paint1;
        }else{
        p=paint2;
        }
        canvas.drawRect(i*tileSize, j*tileSize, tileSize, tileSize, paint);
    }

}
}
}