手写Promise

const url = "https://www.binance.com/bapi/haodesk/v3/friendly/haodesk/std/base-info";

function getData(url) {
   return new Promise((resolve,reject) => {
        const xhr = new XMLHttpRequest();
        xhr.open('GET',url);
        xhr.send();
        xhr.addEventListener('load',function() {
            const result = JSON.parse(xhr.response);
         
            if(result.code === '000000') {
                resolve(result.data);
            }else {
                reject(res.message);
            }
        })
    })
}

getData(url)
    .then(res=>{
        console.log('res',res)
    })
    .catch(err=>{
        console.log('err',err)
    })