javascript - 基于文件下载的进度条

Question

如何根据在 node webkit 中下载的文件显示进度条？

var https = require('https');
var fs = require('fs');
var exec = require('child_process').exec;

var file = fs.createWriteStream("update_setup.exe");
var len = 0; 
var request = https.get(url + 'appdata/update_setup.exe', function (response) {
  response.pipe(file);
  response.on('data', function (chunk) {
    file.write(chunk);
    len += chunk.length;
    var percent = (len / response.headers['content-length']) * 100;
  });
  file.on('finish', function () {
    setTimeout(function () { win.close(); exec('update_setup.exe'); }, 1000);
  });
});

Answer 1

读取响应的 content-length header 并将其与已下载的字节数进行比较。

var http = require('http');
var fs = require('fs');

var file = fs.createWriteStream('dest');
var len = 0;

http.get(url, function(res) {
  res.on('data', function(chunk) {
    file.write(chunk);
    len += chunk.length;

    // percentage downloaded is as follows
    var percent = (len / res.headers['content-length']) * 100;
  });
  res.on('end', function() {
    file.close();
  });
  file.on('close', function() {
    // the file is done downloading
    exec('update_setup.exe');
  });
});

此代码检查接收到的数据的长度并将其添加到len。将 len 除以文件的总大小，然后乘以一百得到一个百分比。