使用阿里云函数作为微信授权后台接口

 创建HTTP触发器函数，选择node.js

var getRawBody = require('raw-body');
var getFormBody = require('body/form');
var http = require('https');

var querystring = require('querystring');

var body = require('body');
module.exports.handler = function(req, resp, context) {
     getRawBody(req, function (err, data) {
        var result = JSON.parse(data);
        var jsCode = result.jsCode;
        if(jsCode!=null&&jsCode!=null){
            //get 请求外网  
            var options = { 
                hostname: 'api.weixin.qq.com', 
                path: '/sns/jscode2session?appid=wx98a7c228xxxxx&secret=0a2b35320f7ab2398ff9c8c2xxxxxx&js_code='+jsCode+'&grant_type=authorization_code', 
                method: 'GET' 
            }; 
           var httpReq = http.request(options, function (res) { 
                res.setEncoding('utf8'); 
                res.on('data', function (chunk) { 
                    resp.send(JSON.stringify(chunk));
                }); 
            }); 
            
            httpReq.on('error', function (e) { 
                console.log('problem with request: ' + e.message); 
                resp.send(JSON.stringify('problem with request: ' + e.message));
            });           
            httpReq.end(); 
        }       
     });
}

测试结果（我这jscode是随便写的，正式环境测试能返回openid）：