ajax兼容方法

function createXhr() {

let xhr = null;

if (window.XMLHttpRequest) {

xhr = new XMLHttpRequest();

} else {

if (new ActiveXObject('Microsoft.XMLHTTP')) {

xhr = new ActiveXObject('Microsoft.XMLHTTP');

} else if (new ActiveXObject('Msxml2.XMLHTTP')) {

xhr = new ActiveXObject('Msxml2.XMLHTTP');

} else if (new ActiveXObject('Msxml3.XMLHTTP')) {

xhr = new ActiveXObject('Msxml3.XMLHTTP');

}

}

return xhr;

}

let xhr = createXhr();

xhr.open('get', 'http://127.0.0.1:8060/getUsers', true);

xhr.onreadystatechange = function () {

};

xhr.send();