Detect support for background-attachment: fixed?

Question

Is there a way to detect browser support for background-attachment: fixed?

Edit: Although this feature is widely supported on desktop browsers it is poorly supported

Answer 1

You might look at document.body.style and make sure that

• there's a property there called "backgroundAttachment", and
• you can set it to "fixed", and it retains its value when you do so.

Chrome, FF, Opera, and Safari all ignore attempts to set the property to an invalid value. IE9 throws an exception when you try. So if either one happens, that value definitely isn't supported. (If the browser just blindly sets the value and retains it, then it still might not work. But at that point, you really can't the browser to tell you much anyway.)

function supportsFixedBackground() {
    try {
        var style = document.body.style;
        if (!("backgroundAttachment" in style)) return false;
        var oldValue = style.backgroundAttachment;
        style.backgroundAttachment = "fixed";
        var isSupported = (style.backgroundAttachment === "fixed");
        style.backgroundAttachment = oldValue;
        return isSupported;
    }
    catch (e) {
        return false;
    }
}

I don't bother with IE6 anymore, and don't have another browser handy that doesn't support fixed backgrounds, so i'm unable to test setting "fixed".