Can see the screen size

<body> <p id="width-txt"></p> <p id="height-txt"></p> </body>

const body = document.getElementsByTagName("body")[0]; function resize() { const width = window.innerWidth; const height = window.innerHeight; document.getElementById("width-txt").textContent = `width = ${width}px`; document.getElementById("height-txt").textContent = `height = ${height}px`; body.style.width = width + "px"; body.style.height = height + "px"; } window.addEventListener("resize", resize); resize();