实现带有超时功能的promise

let rest = function (_data = 4000) {
return Promise.race([
upload(),
Timeout(_data)
])
}
function upload() {
console.log('请求进行中...');
return new Promise((resolve, reject) => {
//模拟的接口
setTimeout(() => {
resolve({ data:{code:200,data:[]} })
}, 2000);
// 向外暴露取消函数
cancelFn = function (msg) {
reject('请求超时，请重试');
}

})
};
function Timeout(times) {
return new Promise((resolve, reject) => {
setTimeout(() => {
cancelFn();
}, times)
})
}
let res= rest()
res.then(res=>{
console.log(res);
})