如何在网页上获取系统属性？

// 获取屏幕尺寸
var screenWidth = window.innerWidth || document.documentElement.clientWidth || document.body.clientWidth;
var screenHeight = window.innerHeight || document.documentElement.clientHeight || document.body.clientHeight;

// 获取浏览器类型
var userAgent = navigator.userAgent;
var browser = "";
if (userAgent.indexOf("Chrome") > -1) {
    browser = "Chrome";
} else if (userAgent.indexOf("Firefox") > -1) {
    browser = "Firefox";
} else if (userAgent.indexOf("Safari") > -1) {
    browser = "Safari";
} else if (userAgent.indexOf("Opera") > -1) {
    browser = "Opera";
} else if (userAgent.indexOf("MSIE") > -1) {
    browser = "IE";
}

// 获取操作系统类型
var os = "";
if (navigator.appVersion.indexOf("Win") != -1) os = "Windows";
if (navigator.appVersion.indexOf("Mac") != -1) os = "MacOS";
if (navigator.appVersion.indexOf("X11") != -1) os = "UNIX";
if (navigator.appVersion.indexOf("Linux") != -1) os = "Linux";

function getUserIP() {
    $client_ip = '';
    if (getenv('HTTP_CLIENT_IP')) {
        $client_ip = getenv('HTTP_CLIENT_IP');
    } else if (getenv('HTTP_X_FORWARDED_FOR')) {
        $client_ip = getenv('HTTP_X_FORWARDED_FOR');
    } else if (getenv('HTTP_X_FORWARDED')) {
        $client_ip = getenv('HTTP_X_FORWARDED');
    } else if (getenv('HTTP_FORWARDED_FOR')) {
        $client_ip = getenv('HTTP_FORWARDED_FOR');
    } else if (getenv('HTTP_FORWARDED')) {
        $client_ip = getenv('HTTP_FORWARDED');
    } else if (getenv('REMOTE_ADDR')) {
        $client_ip = getenv('REMOTE_ADDR');
    } else {
        $client_ip = 'UNKNOWN';
    }
    return $client_ip;
}