canvas005

HTML

<canvas width="500" height="500" id="canvas"></canvas>

JavaScript

var canvas = document.getElementById('canvas');
var ctx = canvas.getContext('2d');

var speed=3;
var start = {x:0,y:0};
var point = {x:0,y:0};
var angle = 45;
var radians = angle * Math.PI / 180;
var moveX = Math.cos(radians)*speed;
var moveY = Math.sin(radians)*speed;

setTimeout(function(){
    ctx.clearRect(0,0,500,500);
    ctx.fillRect(point.x,point.y,100,100);
    point.x += moveX;
    point.y += moveY;
    setTimeout(arguments.callee, 20);
},1);