环境判断：区别h5打开还是weixin打开？

var source_platform = '' , pf_source = 2; //系统平台
    //区别是否是 微信浏览器 , source_platform 系统平台  2018.12.6新增
    var ua = navigator.userAgent, source_platform = '';
    if (ua.match(/MicroMessenger/i) == 'MicroMessenger'){
        //微信浏览器
        source_platform = 'weixin';
        pf_source = 3;
    }else {
        source_platform = 'H5';
        pf_source = 2;
    }