自定义axios库

简单的实现

function axios({url,method='GET',params={},data={}}) {
    return new Promise((resolve,reject) => {
        //创建xml对像
        const xhr = new XMLHttpRequest();
        let queryString = '';
        Object.keys(params).forEach(key => {
            queryString += `${key} = ${params[key]}&`
        });
        if(queryString) {
            queryString = queryString.substring(0,queryString.length - 1);
            url += '?' + queryString;
        }
        //打开连接
        xhr.open(method,url,true);
        //发送请求
        if(method === 'GET') {
            xhr.send();
        } else if(method === 'POST') {
            //设置请求状
            xhr.setRequestHeader('Content-Type','application/json;charset=utf-8')
            xhr.send(JSON.stringify(data))
        }
        //绑定状态的临听
        xhr.onreadystatechange = (req) => {
            if(xhr.readyState !==4) {
                return
            }
            const { status,statusText } = xhr;
            if(status >= 200 && status <=299) {
                const response = {
                    data:JSON.parse(xhr.response),
                    status,
                    statusText
                }
                console.log('response',response);
                resolve(response);
            } else {
                reject(new Error('request error status is' + status))
            }
        }
    })
}

module.exports = axios;

axios语法