???var xhr = new XMLHttpRequest() ???????xhr.onreadystatechange = function(){//状态触发事件 ???????if(xhr.readyState == 4){ ???????????if(xhr.status >=200 && xhr.status<300 || xhr.status == 304){ ???????????????console.log(xhr) ???????????}else{ ???????????????console.log(xhr.status) ???????????} ???????} ???} ???xhr.onprogress = function(event){//浏览器接受新数据期间周期性触发 ???????if(event.lengthComputable){ ???????????console.log(event.total) ???????} ???} ???????xhr.open(‘get‘,‘data/cart.json‘,true); ???xhr.setRequestHeader(‘myheader‘,‘myvalue‘)//可以设置自定义头部信息 ???xhr.send(null)//接收一个参数，即要作为请求主体发送的数据，若无，为了浏览器兼容，必须传入null。 ???????//跨域jsonp ???function handleResponse(response){ ???????console.log(response.ip,response.city,response.region_name) ???} ???????var script = document.createElement(‘script‘) //script和img一样有能力不受限制从其他域加载资源 ???script.src = ‘http://freegeoip.net/json/?callback=handleResponse‘; ????document.body.insertBefore(script,document.body.firstChild)ajax与jsonp
原文地址：https://www.cnblogs.com/wangxi01/p/8400595.html