function aaa() {

        const promise = new Promise(function (resolve, reject) {

            const xmlhttp = new XMLHttpRequest();

            xmlhttp.open("post", "url");

            xmlhttp.setRequestHeader("content-type", "application/x-www-form-urlencoded");

            xmlhttp.onreadystatechange = function () {

                if (this.readyState != 4) {

                    return;

                }

                if (this.status == 200) {

                    resolve(this.response);

                } else {

                    reject(new Error("数据请求失败"))

                }

            }

            xmlhttp.send("");

        })

        return promise;

    }

//then处理数据

let bbb = aaa();

    bbb.then(function (value) {

        var data = JSON.parse(value);

        for (let i of Object.values(data)) {

            var name = i.name_coach;

            document.getElementById("ul").innerHTML += "<li>" + name + "</li>";

        }

    }, function (error) {

        alert(error);

    })