JAVASCRIPT

canvas full screen js

(window.onresize = () => {
	canvas.width = innerWidth, canvas.height = innerHeight;
})();

// Condensed
(window.onresize=e=>{canvas.width=innerWidth,canvas.height=innerHeight})()

make canvas cover whole screen in html

function resize() {
    canvas.width = window.innerWidth;
    canvas.height = window.innerHeight;
    render();
}
window.addEventListener('resize', resize, false); resize();
function render() { // draw to screen here
}