用promise封装原生ajax请求

// 简单的ajax原生实现

var url = 'https://hq.tigerbrokers.com/fundamental/finance_calendar/getType/2017-02-26/2017-06-10';

var result;

var XHR = new XMLHttpRequest();

XHR.open('GET', url, true);

XHR.send();

XHR.onreadystatechange = function() {

if (XHR.readyState == 4 && XHR.status == 200) {

result = XHR.response;

console.log(result);

}

}

var url = 'https://hq.tigerbrokers.com/fundamental/finance_calendar/getType/2017-02-26/2017-06-10';

// 封装一个get请求的方法

function getJSON(url) {

return new Promise(function(resolve, reject) {

var XHR = new XMLHttpRequest();

XHR.open('GET', url, true);

XHR.send();

XHR.onreadystatechange = function() {

if (XHR.readyState == 4) {

if (XHR.status == 200) {

try {

var response = JSON.parse(XHR.responseText);

resolve(response);

} catch (e) {

reject(e);

}

} else {

reject(new Error(XHR.statusText));

}

}

}

})

}

getJSON(url).then(res => console.log(res));