js http请求封装

function ajax(opt) {
             opt = opt || {};
             opt.method = opt.method.toUpperCase() || 'POST';
             opt.url = opt.url || '';
             opt.async = opt.async || true;
             opt.data = opt.data || null;
             opt.success = opt.success || function () {};
             var xmlHttp = null;
             if (XMLHttpRequest) {
                 xmlHttp = new XMLHttpRequest();
            }
             else {
                 xmlHttp = new ActiveXObject('Microsoft.XMLHTTP');
             }var params = [];
             for (var key in opt.data){
                 params.push(key + '=' + opt.data[key]);
             }
             var postData = params.join('&');
             if (opt.method.toUpperCase() === 'POST') {
                 xmlHttp.open(opt.method, opt.url, opt.async);
                 xmlHttp.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded;charset=utf-8');
                 xmlHttp.send(postData);
             }
             else if (opt.method.toUpperCase() === 'GET') {
                 xmlHttp.open(opt.method, opt.url + '?' + postData, opt.async);
                 xmlHttp.send(null);
             } 
             xmlHttp.onreadystatechange = function () {
                 if (xmlHttp.readyState == 4 && xmlHttp.status == 200) {
                     opt.success(xmlHttp.responseText);
                 }
             };
        }

//调用
ajax({
             method: 'GET',
             url: 'https://www.cnblogs.com/a757956132/p/5603176.html',
             data: {
                 name1: 'value1',
                 name2: 'value2'
             },
             success: function (response) {
                console.log(response);
             }
        }); 
//      ajax({
//           method: 'POST',
//           url: 'test.php',
//           data: {
//               name1: 'value1',
//               name2: 'value2'
//           },
//           success: function (response) {
//              console.log(response)；
//           }
//      });