MininDM,
<!DOCTYPE html>
<html>
<body>
<canvas id="myCanvas" width="300" height="150" style="border:1px solid #d3d3d3;">
Your browser does not support the HTML5 canvas tag.</canvas>
<script>
//функция переключения день/ночь
function timeColor() {
var now = new Date();
var hours = now.getHours();
var color = "#FF0000";
if(hours >= 18 || hours < 9)
color = "#000000"
return color;
}
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.fillStyle = timeColor();
ctx.fillRect(20, 20, 150, 100);
</script>
</body>
</html>