javascript - 封装ajax

封装，使用有示例.

     // 封装示例：
     function ajax(url, method, params, done) {
       var xhr = null;
       method = method.toUpperCase();
       xhr = window.XMLHttpRequest ? xhr = window.XMLHttpRequest : xhr = new ActiveXObject('Microsoft.XMLHTTP');

       if (typeof params === 'object') {
         var tempArr = [];
         for (var key in params) {
           var value = params[key];
           tempArr.push(key + '=' + value);
         }
         params = tempArr.join('&');
       }

       // GET
       if (method === 'GET') {
         url += '?' + params;
       }
       xhr.open(method, url, false);

       // POST
       var data = null;
       if (method === 'POST') {
         xhr.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded');
         data = params;
       }

       xhr.onreadystatechange = function () {
         if (this.readyState !== 4 && this.status !== 200) return false;
         ongone(this.responseText);
       }
       xhr.send(data);
     }

     // 调用示例：ajax('get','test.php',{id:123,},ongone)
38     ajax('GET', 'test.php', {}, ongone);
39
40     var ongone = function (res) {
41       console.log('1');
42       console.log('2');
43       console.log(res);
44       console.log('gone!');
45     }