How to Animate Graphics on an HTML5 Canvas? (A Simple Example)
Use requestAnimationFrame() to implement HTML5 Canvas animation: first obtain the canvas and 2D context, and then loop to clear, update properties, and redraw; you can add collision detection, user interaction, and timing control.
To animate graphics on an HTML5 <canvas></canvas> , you repeatedly clear the canvas, update object properties (like position or color), and redraw—typically using requestAnimationFrame() for smooth, efficient frame timing.
Set up the canvas and context
Start by getting a reference to the canvas element and its 2D rendering context. This is your drawing surface and toolset.
- Use
document.getElementById()orquerySelector()to grab the canvas - Call
getContext('2d')to enable drawing commands - Optionally set canvas width/height explicitly (avoid CSS scaling—it blurs graphics)
Draw a simple moving shape
For example, animate a red circle moving across the screen:
- Define variables like
x,y, anddx(horizontal speed) - In each frame: clear the canvas with
clearRect(), updatex = dx, then draw the circle witharc()andfill() - Bounce it by reversing
dxwhenxhits the left or right edge
Use requestAnimationFrame for smooth animation
Instead of setTimeout or setInterval , use requestAnimationFrame(callback) . It syncs with the browser's refresh rate (~60fps) and pauses when the tab is inactive.
- Call it at the end of your draw function to schedule the next frame
- Pass the same function recursively:
function animate() { /* draw logic */ requestAnimationFrame(animate); } - Start it once with
animate()— no loops needed
Add interactivity or timing control
You can make animation respond to user input or run for a set duration:
- Listen for
keydownto change speed or direction - Use
performance.now()to track elapsed time for easing, delays, or state changes - Stop animation by skipping the next
requestAnimationFramecall — no need to “cancel” it
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