第一次发帖，还望社区的前辈不吝赐教

最近做一个 rails 项目的浏览器适配，出现了这样的问题： development 模式，一切正常 production 模式，压缩并预编译了 js，然后在 ie8 下就报 js 错误了，但在 chrome 下是正常的

去掉下面的 config.assets.js_compressor = :uglifier，ie8 下就没问题了

config.assets.compile = true

# Raises error for missing translations
# config.action_view.raise_on_missing_translations = true
config.assets.js_compressor = :uglifier
config.assets.css_compressor = :sass

以下是 jquery 源码，控制台中显示报错的位置在下面第一行，错误是'undefined' 为空或不是对象

// Ensure firing before onload, maybe late but safe also for iframes
    document.attachEvent( "onreadystatechange", completed );

    // A fallback to window.onload, that will always work
    window.attachEvent( "onload", completed );

    // If IE and not a frame
    // continually check to see if the document is ready
    var top = false;

    try {
        top = window.frameElement == null && document.documentElement;
    } catch ( e ) {}

困扰一天了，望大神解惑