Axios作为官方Vue推荐的Ajax插件，在连接超时timeout之后，不会再次主动连接，从而导致下次Ajax请求后端服务接口会报404错误。借助Github的分享，记录一下解决方案。

axios.defaults.retry = 4;
axios.defaults.retryDelay = 1000;

axios.interceptors.response.use(undefined, function axiosRetryInterceptor(err) {
    var config = err.config;
    // If config does not exist or the retry option is not set, reject
    if(!config || !config.retry) return Promise.reject(err);
    
    // Set the variable for keeping track of the retry count
    config.__retryCount = config.__retryCount || 0;
    
    // Check if we've maxed out the total number of retries
    if(config.__retryCount >= config.retry) {
        // Reject with the error
        return Promise.reject(err);
    }
    
    // Increase the retry count
    config.__retryCount += 1;
    
    // Create new promise to handle exponential backoff
    var backoff = new Promise(function(resolve) {
        setTimeout(function() {
            resolve();
        }, config.retryDelay || 1);
    });
    
    // Return the promise in which recalls axios to retry the request
    return backoff.then(function() {
        return axios(config);
    });
});