function openfield(a,b) {
	if(a<0 || b<0 || a>fieldSizeX-1 || b>fieldSizeY-1) return;
	cellArray[nx][ny].isClicked = true;
	cellclick = document.getElementById(a+'-'+b);
	if(!cellclick) return;
	cellclick.className = 'cell-clicked';
	cellclick.appendChild(document.createTextNode(cellArray[a][b].cellVal));
	if(cellArray[a][b].cellVal == " ") {
		for(var x=a-1;x<=a+1;x++)
			for(var y=b-1;y<=b+1 && !(x==a&&y==b);y++)
				openfield(x,y);
	}
}