javascript acces an item of an array? -

i'm beginner javascript used pixi.

i don't know how format array row , line. try snippet when want access specific value of array :

alert(graphics[2][1].position.x) 

i have error :

uncaught typeerror: cannot read property '1' of undefined(anonymous function) @ main.js:40

here complete snippet :

var renderer = pixi.autodetectrenderer(800, 600,{backgroundcolor : 0x1099bb}); document.body.appendchild(renderer.view);  var stage = new pixi.container();  var container = new pixi.container()  stage.addchild(container);  (var j = 0; j < 5; j++) {     (var = 0; < 5; i++) { var graphics = new pixi.graphics();  graphics.beginfill(0xff3300); graphics.linestyle(4, 0xffd900, 1); graphics.drawrect(0,0,10,10); graphics.position.x= 40 * i; graphics.position.y=40 * j; container.addchild(graphics);     }; };  alert(graphics[2][1].position.x)//here error  container.x=100 container.y=100 container.scale.x=container.scale.y=.1;  animate();  function animate() {     requestanimationframe( animate );      container.rotation += .1;     renderer.render(stage); } 

if want have 2d array need use code:

var graphics = []; (var j = 0; j < 5; j++) {     graphics[j] = [];     (var = 0; < 5; i++) {         graphics[j][i] = new pixi.graphics();          graphics[j][i].beginfill(0xff3300);         graphics[j][i].linestyle(4, 0xffd900, 1);         graphics[j][i].drawrect(0,0,10,10);         graphics[j][i].position.x = 40 * i;         graphics[j][i].position.y = 40 * j;         container.addchild(graphics[j][i]);     }; }; 

then able call this:

alert(graphics[2][1].position.x);