javascript - Uncaught TypeError: cannot set property 'x' of undefined -

as part of first code trying make array randomly generated circles (stars).

this line typeerror occurs.

stars[i].x = math.floor(math.random() * w) 

i looked through code , stars defined.

$(document).ready(function() { //canvas var canvas = $("#canvas")[0]; var ctx = canvas.getcontext("2d"); var w = $("#canvas").width(); var h = $("#canvas").height(); var stars = []; 

the rest of code fine might have here see else may have gone wrong.

$(document).ready(function() { //canvas var canvas = $("#canvas")[0]; var ctx = canvas.getcontext("2d"); var w = $("#canvas").width(); var h = $("#canvas").height(); var stars = [];   function init() {     createstars();     drawstars(); }  init();  function createstars() {     (var i=0; i<=4; i++) {         stars[i].x = math.floor(math.random() * w);         stars[i].y = math.floor(math.random() * h);     } }  function drawstars() {     (var i=0; <= 4; i++) {         ctx.beginpath();         ctx.arc(stars[i].x, stars[i].y, 10, 0, 2 * math.pi);         ctx.stroke();     } } }); 

this first program ever i'm not entirely sure debugging process. thank in advance.

start array defined, stars[i] object there? need explicetly create objects:

function createstars() {     (var i=0; i<=4; i++) {         stars[i] = {};         stars[i].x = math.floor(math.random() * w);         stars[i].y = math.floor(math.random() * h);     } } 

or more concise syntax:

function createstars() {     (var i=0; i<=4; i++) {         stars[i] = {             x: math.floor(math.random() * w),             y: math.floor(math.random() * h)         };     } }