原生ajax请求

    // ajax四步：创建XMLHttpRequest对象，连接服务器，发送请求，接收响应数据
        ajax: function (options) {
            options = options || {};
            options.type = (options.type || "GET").toUpperCase();
            options.dataType = options.dataType || ‘json‘;
            var xhr = new XMLHttpRequest();
            var arr = [];
            if (options.params) {
                for (var key in options.params) {
                    arr.push(encodeURIComponent(key) + "=" + encodeURIComponent(options.params[key]))
                }
                var postData = arr.join("&")
                options.url = options.url + "?" + postData
            }
            xhr.onreadystatechange = function () {
                if (xhr.readyState == 4) {
                    var status = xhr.status;
                    if (status >= 200 && status < 300) {
                        try {
                            options.success && options.success(JSON.parse(xhr.responseText))
                        } catch (e) {
                            options.success && options.success(xhr.responseText)
                        }
                    } else {
                        options.fail && options.fail(status)
                    }
                }
            }
            if (options.type == "GET") {
                xhr.open("GET", options.url, true)
                xhr.send(null)
            } else if (options.type == "POST") {
                xhr.open("POST", options.url, true)
                xhr.setRequestHeader("Content-Type", "application/json")
                xhr.send(JSON.stringify(options.data))
            }
        },

    login.ajax({
                    url: ‘/login‘,
                    type: ‘POST‘,
                    params: {
                        Phone: phone
                    },
                    success: function (response) {
              
                    },
                    fail: function (status) {

                    }
                })