Internet Explorer Version detection and append a ie class to the body

gistfile1.js

var internetExplorerVersion = (function (){
    if (window.ActiveXObject === undefined) return null;
    if (!document.querySelector) return 7;
    if (!document.addEventListener) return 8;
    if (!window.atob) return 9;
    if (!document.__proto__) return 10;
    return 11;
})();

if (internetExplorerVersion) {
    if (internetExplorerVersion == 8) {
        document.getElementsByTagName('body')[0].className+=' ie8'
    }
    else if (internetExplorerVersion == 9) {
        document.getElementsByTagName('body')[0].className+=' ie9'
    }
    else if (internetExplorerVersion == 10) {
        document.getElementsByTagName('body')[0].className+=' ie10'
    }
    else {
        document.getElementsByTagName('body')[0].className+=' ie'
    }
}