promise实例

let $http = {
		post:function(url,params){
			let promise = new Promise(function(resolve, reject){
				$.ajax({
					url:url,
					method:'post',
					data:params?params:null,
					complete:function(res){
						if(this.status === 200 || this.status === 304) {
							resolve(res);
						} else {
							reject(new Error(this.statusText));
						}
					}
				});
			});
			return promise;
		}
	};

调用：

$http.post('http://url.com').then((res)=>{
					if(res.success==true) {
						console.success(res;
					}
				})
                .catch((err)=>{
				    console.error(err);
                });