微信网页开发，动态修改页面Title

Fucntion如下：

xxx.setDocumentTitle = function(title) {
    document.title = title;
    if (/ip(hone|od|ad)/i.test(navigator.userAgent)) {
        var i = document.createElement('iframe');
        i.src = '/favicon.ico';
        i.style.display = 'none';
        i.onload = function() {
            setTimeout(function(){
                i.remove();
            }, 9)
        }
        document.body.appendChild(i);
    }
}