通过js userAgent来判断

判断访问此链接的操作系统

var Agents = new Array("Android", "iPhone", "SymbianOS", "Windows Phone", "iPad", "iPod");
var flag = true;

/**
 * 初始化加载程序
 */
window.onload = function(){
    console.log(isMobile());
    console.log(isWechat());
    console.log(getOsVersion());
}

/**
 * 判断是不是移动端
 * @returns {boolean}
 */
function isMobile() {
    var userAgentInfo = navigator.userAgent;
    for (var v = 0; v < Agents.length; v++) {
        if (userAgentInfo.indexOf(Agents[v]) > 0) {
            flag = false;
            break;
        }
    }
    document.write("是否移动端-"+ !flag+"//");
    return "是否移动端-" + !flag;
}

/**
 * 判断是不是微信浏览器
 * @returns {boolean}
 */
function isWechat() {
    var ua = navigator.userAgent.toLowerCase();

    if(ua.match(/MicroMessenger/i)=="micromessenger"){
        document.write("是微信浏览器//");
        return "是微信浏览器";
    }
    else{
        document.write("不是微信浏览器//");
        return "不是微信浏览器";
    }
}

/**
 * 判断浏览器所在机器操作系统版本
 */
function getOsVersion(){
    var u = navigator.userAgent,version = '';
    if (u.indexOf('Mac OS X') > -1) {
        //ios
        var regStr_saf = /OS [\d._]*/gi;
        var verinfo = u.match(regStr_saf);
        version ="ios" + (verinfo + "").replace(/[^0-9|_.]/ig,'').replace(/_/ig,'.');
        document.write("ios");
    } else if (u.indexOf('Android') > -1
        || u.indexOf('Linux') > -1) {
        //android
        version ="android" + u.substr(u.indexOf('Android') + 8, u.indexOf(";", u.indexOf("Android")) - u.indexOf('Android') - 8);
        document.write("android");
    } else if (u.indexOf('BB10') > -1) {
        //黑莓bb10系统
        version ="黑莓bb10系统" +  u.substr(u.indexOf('BB10') + 5, u.indexOf(";", u.indexOf("BB10")) - u.indexOf('BB10') - 5);
        document.write("黑莓bb10系统");
    } else if (u.indexOf('IEMobile')) {
        //windows phone
        version ="windows phone";
        document.write("windows phone")
    }
    return version;
}