CSS - Scale (Zoom Factor)

Scale is the zoom level of a page is first loaded.

When the zooming factor is exactly 100%, one CSS pixel equals one device pixel.

The scale when the page is loaded is defined by the viewport meta tag

The maximum-scale, minimum-scale, and user-scalable properties are defined by the viewport meta tag

You can calculate that factor by dividing screen.width by window.innerWidth

onResize = function () {
     zoomFactor=window.innerWidth/screen.width; 
     console.log("The Zooming factor is "+zoomFactor);
}
onResize();

window.onresize = function () {
     zoomFactor=window.innerWidth/screen.width; 
     console.log("The Zooming factor is "+zoomFactor);
}