封装ajax-3(通过promise内层封装)

let ajax = (function (window) {
function uri(obj){
let arr=[];
if (obj && typeof obj === 'object') {
for(let i in obj){
arr.push(encodeURIComponent(i)+'='+encodeURIComponent(obj[i]));
}
}
return arr.join('&');
}
return function (options) {
return new Promise((resolve, reject) => {
let _options = {
method: 'GET',
async: 'true',
data: 'null'
};
for (let i in options) {
_options[i] = options[i];
}
let xhr;
if (window.XMLHttpRequest) {
xhr = new XMLHttpRequest();
}
else {
xhr = new ActiveXObject('Microsoft.XMLHttp');
}
if (_options.method === 'GET') {
_options.url = `${_options.url}?m=${Math.random()}&${_options.data}`;
}
else {
_options.url = `${_options.url}?m=${Math.random()}`;
}
xhr.open(_options.method, _options.url, _options.async);
_options.data = uri(_options.data);
if (_options.method === 'GET') {
xhr.send(_options.data);
}
else {
xhr.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
xhr.send(_options.data);
}
if (_options.async === false) {
if (xhr.status === 200) {
resolve(JSON.parse(xhr.responseText));
}
else {
reject(xhr.status);
}
}
else {
xhr.onreadystatechange = function () {
if (xhr.readyState === 4) {
if (xhr.status === 200) {
resolve(JSON.parse(xhr.responseText));
}
else {
reject(xhr.status);
}
}
}
}
})
}
})(window);