简单封装一个AJAX

function myAxios(method, url) {
        return new Promise((resolve, reject) => {
            const xhr = new XMLHttpRequest()
            xhr.onreadystatechange = function () {
                if (xhr.readyState === 4) {
                    if (xhr.status >= 200 && xhr.status < 300 || xhr.status === 304) {
                        resolve(xhr.responseText)
                    } else {
                        reject('error')
                    }
                }
            }
            xhr.open(method, url, true)
            xhr.send()
        })
}