原文教程：

1、我的场景是请求 csv 文件，我希望获取下载进度。下面是各种实现的代码。

2、如果是上传进度可能不太一样。有必要的话将来回来补充。

3、如果是请求正常接口的话，似乎无法获得进度，是一步到位的。也就是： { loaded: 【文件总大小】,total: 0 }。所以无法用于请求普通接口。

axios 请求下载文件时的进度条事件

;(async () => {
    // 启动计时器
    console.time('📝耗时统计：')
    // your code...
    await axios({
        url: './全量数据-20220309144842.csv',
        method: 'get',
        onDownloadProgress(progress) {
            const step = Math.round(progress.loaded / progress.total * 100)
            console.log(step + '%')
    }).then(res => {
        console.log('正在解析...')
        const data = csvJSON(res.data)
        console.log('解析完成', data)
    // 停止计时，输出时间
    console.timeEnd('📝耗时统计：')
})();

ajax 请求下载文件时进度条事件

var xhrOnProgress = function (fun) {
    return function () {
        var xhr = $.ajaxSettings.xhr()
        xhr.onprogress = fun
        return xhr
$.ajax({
    type: 'GET',
    url: './全量数据-20220309144842.csv',
    xhr: xhrOnProgress(function (progress) {
        const percent = Math.round(progress.loaded / progress.total * 100)
        console.log(percent + '%')
fetch 请求下载文件时进度条事件
/* https://javascript.info/fetch-progress */
;(async () => {
    // Step 1: start the fetch and obtain a reader
    let response = await fetch('./全量数据-20220309144842.csv');
    const reader = response.body.getReader();
    // Step 2: get total length
    const contentLength = +response.headers.get('Content-Length');
    // Step 3: read the data
    let receivedLength = 0; // received that many bytes at the moment
    let chunks = []; // array of received binary chunks (comprises the body)
    while (true) {
        const { done, value } = await reader.read();
        if (done) {
            break;
        chunks.push(value);
        receivedLength += value.length;
        console.log(`Received ${receivedLength} of ${contentLength}`, )
        const percent = Math.round(receivedLength / contentLength * 100)
        console.log(percent + '%')
    // Step 4: concatenate chunks into single Uint8Array
    let chunksAll = new Uint8Array(receivedLength); // (4.1)
    let position = 0;
    for (let chunk of chunks) {
        chunksAll.set(chunk, position); // (4.2)
        position += chunk.length;
    // Step 5: decode into a string
    let result = new TextDecoder("utf-8").decode(chunksAll);
    // We're done!
    console.log(20220309231613, result)
})();