How can you get the CSS pixel / device pixel ratio?

Question

I want to find the ratio between CSS pixels and device pixels.

Edit: I should have realized that this is just zoom level. I\'ve added an answer to t

Answer 1

You can always use the following method and it would work in all the browsers

window.getDevicePixelRatio = function () {
    var ratio = 1;
    // To account for zoom, change to use deviceXDPI instead of systemXDPI
    if (window.screen.systemXDPI !== undefined && window.screen.logicalXDPI       !== undefined && window.screen.systemXDPI > window.screen.logicalXDPI) {
        // Only allow for values > 1
        ratio = window.screen.systemXDPI / window.screen.logicalXDPI;
    }
    else if (window.devicePixelRatio !== undefined) {
        ratio = window.devicePixelRatio;
    }
    return ratio;
};