SOURCE

var browser = navigator.userAgent;
var weixin = browser.match(/MicroMessenger/ig);
var iphone = browser.match(/iPhone/ig);
var ipad = browser.match(/iPad/ig);
var android = browser.match(/Android/ig);

if (weixin) {
    document.getElementById('info').innerHTML = "微信";
} else if (iphone) {
    document.getElementById('info').innerHTML = "iphone";
} else if (ipad) {
    document.getElementById('info').innerHTML = "ipad";
} else if (android) {
    document.getElementById('info').innerHTML = "android";
} else {
    document.getElementById('info').innerHTML = "PC";
}

你的设备是：<span id="info"> </span>