const getJSON = function(url,type,data) {
const promise = new Promise(function(resolve, reject){
const handler = function() {
if (this.readyState !== 4) {
return;
};
if (this.status === 200) {
resolve(this.response);
} else {
reject(new Error(this.statusText));
}
};
const client = new XMLHttpRequest();
client.open(type, url);
client.onreadystatechange = handler;
client.responseType = "json";
if(type==‘get‘){
client.send();
}else {
client.setRequestHeader("Content-Type","application/json");//data只能是JSON字符串
client.send(JSON.stringify(data)) //post请求传入string
}
});
return promise;
};
调用案例
$(function() {
$("button").click(function() {
getJSON(‘http://localhost:3000/info‘,‘get‘).then( res => {
//success
console.log(‘ok‘);
}).catch( res=> {
console.error(‘出错了‘, error);
});
});
//JQUERY 1.5.0返回的是xhr对象 高于1.5.0返回的deferred对象
})
封装promise
原文：https://www.cnblogs.com/shiapi/p/9257717.html
