一个不一样的ajax

/**
 * @author huangteng
 * @description a new ajax func sync
 * @version 1.0.0
 * @param url 地址
 * @param body 参数对象
 * @param method 访问方式
 * @note: 最佳实践是用es6语法，这里使用的es5
 * @modified by:
 * @modified time:
 */
var xhr = function(url,body,method){
    this.url = url
    this.body = body
    this.method = method || 'GET'
    var defer = $.Deferred()

    $.ajax({
        type: this.method,
        url:  this.url,
        data: this.body,
        beforeSend: function(request){
          request.setRequestHeader('Content-type','application/json')
        }
    })
    .done(defer.resolve)
    .fail(defer.reject)

    return defer.promise()
}

/**
 * @description how to use
 * @note 支持链式调用
 */
 xhr('http://dxxxx.com1',{name:'jack',pwd:'123'},'POST').then(function(req){
    console.log(req)
 }).fail(function(err){
    console.log(err)
 })