var pictures = new Array(3);
pictures[0] = new Image();
pictures[0].src = "blank.gif";
pictures[1] = new Image();
pictures[1].src = "triangle.gif";
pictures[2] = new Image();
pictures[2].src = "circle.gif";
pictures.check = 0;
pictures.forEach(function(img){
img.onload = function(){
pictures.check++
if(pictures.check == pictures.length){
alert('загрузились все пикчи')
}
}
})