i am working with the javascript to display my div to full screen . i have a function which call on button click and my screen turns into full screen mode but i want the full screen on page load.

what i have tried is

function togglescreen(){
    var element = document.getElementById("video-container");
    element.requestFullscreen();
}

<button id="fullscreenBtn" onclick="togglescreen()">Full Screen</button>
<div id="video-container" width="1000" height="500"></div>

it works perfectly but i need full screen into my page load. i also tried

document.getelementbyId("fullscreenBtn").click();

but it's also not working.