js原生请求

function api(url,fn){

let xhr = new XMLHttpRequest

xhr.open('POST', url, true)

 xhr.setRequestHeader("Content-Type","application/x-www-form-urlencode");

xhr.onreadystatechange = function () {
	if(xhr.readyState == 4 && (xhr.status == 200 || xhr.status == 304)) {
  	fn.call(this, xhr.responseText)
	}
}
xhr.send(data)

}