获取重试请求（失败时） [英] fetch retry request (on failure)

问题描述

我正在使用浏览器的原生获取API 网络请求。此外，我正在为不支持的浏览器使用 whatwg-fetch polyfill。

I'm using browser's native fetch API for network requests. Also I am using the whatwg-fetch polyfill for unsupported browsers.

但是，如果请求失败，我需要重试。现在我找到了这个npm包 whatwg-fetch-retry ，但是他们没有解释如何在他们的文档中使用它。有人可以帮我这个或建议我一个替代方案吗？

However I need to retry in case the request fails. Now there is this npm package whatwg-fetch-retry I found, but they haven't explained how to use it in their docs. Can somebody help me with this or suggest me an alternative?

推荐答案

来自官方提取文档：

fetch('/users')
    .then(checkStatus)
    .then(parseJSON)
    .then(function(data) {
          console.log('succeeded', data)
    }).catch(function(error) {
          console.log('request failed', error)
    })

看到那个捕获？将在获取失败时触发，例如，您可以再次获取。

See that catch? Will trigger when fetch fails, you can fetch again there for example.

查看promises https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise

Have a look at promises https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise

编辑：添加应该返回结果的工作示例。已经尝试过Chrome（v.60.0）并且没有使用任何polyfill，也没有使用你提到的软件包（仔细阅读文档后，它似乎只是来自fetch polifyll的一个分支）。

add working example that should return a result. Have tried in Chrome (v.60.0) and didn't use any polyfill nor the package you mention (after reading carefully the docs it seems its just a fork from fetch polifyll).

function fetchRetry(url, delay, limit, fetchOptions = {}) {
    return new Promise((resolve,reject) => {
        function success(response) {
            resolve(response);
        }
        function failure(error){
            limit--;
            if(limit){
                setTimeout(fetchUrl,delay)
            }
            else {
                // this time it failed for real
                reject(error);
            }
        }
        function finalHandler(finalError){
            throw finalError;
        }
        function fetchUrl() {
            return fetch(url,fetchOptions)
                .then(success)
                .catch(failure)
                .catch(finalHandler);
        }
        fetchUrl();
    });
}

fetchRetry('https://www.google.es',1000,4)  
   .then(function(response){
       if(!response.ok){
           throw new Error('failed!');
       }
       return response;
   })
   .then(function(response){
       console.log(response);
   })
   .catch(function(error){
       console.log(error);
    });

未测试重试尝试是否返回响应，但我想他们确实如此。

Haven't tested if the retry attempts return the response but I suppose they do.

编辑：发现这个包但它取代了fetch API所以我不太确定， https://www.npmjs.com/package/fetch-retry （在第一个google结果页面中还有两个像这样的包，用于获取重试... ）

found this package but it replaces the fetch API so I'm not pretty sure about that, https://www.npmjs.com/package/fetch-retry (there are two more packages like this one in the first google results page for fetch-retry...)

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