Web Uploader在低版本IE下无法显示Flash的一种情况

用户反馈在IE 8下无法正常显示Web Uploader控件，并已安装了Flash插件。调试发现在内部抛出了Runtime Error的错误，关键代码如下：

Runtime.create = function( opts, orders ) {
    var type, runtime;

    orders = orders || Runtime.orders;
    $.each( orders.split( /\s*,\s*/g ), function() {
        if ( factories[ this ] ) {
            type = this;
            return false;
        }
    });

    type = type || getFirstKey( factories );

    if ( !type ) {
        throw new Error('Runtime Error');
    }

    runtime = new factories[ type ]( opts );
    return runtime;
};

可以发现是对应的FlashRuntime并未找到。查看源代码发现在注册FlashRuntime时候有一个版本判断，如果没有符合最低版本要求则不注册。查看用户安装的Flash版本确实低于该要求。

FlashRuntime.register = function( name, component ) {
    component = components[ name ] = Base.inherits( CompBase, $.extend({

        // @todo fix this later
        flashExec: function() {
            var owner = this.owner,
                runtime = this.getRuntime();

            return runtime.flashExec.apply( owner, arguments );
        }
    }, component ) );

    return component;
};

if ( getFlashVersion() >= 11.4 ) {
    Runtime.addRuntime( type, FlashRuntime );
}