原文地址：https://www.cnblogs.com/mo-cha/p/6038872.html

$(function(){
    var system = {
        win: false,
        mac: false,
        xll: false,
        ipad:false
    };
    //檢測平臺
    var p = navigator.platform;
    system.win = p.indexOf("Win") == 0;
    system.mac = p.indexOf("Mac") == 0;
    system.
 
x11 = (p == "X11") || (p.indexOf("Linux") == 0);
    system.ipad = (navigator.userAgent.match(/iPad/i) != null)?true:false;
    if (system.win || system.mac || system.xll ||system.ipad) {     
    } else {
       some code;
    }
})