如何在nodejs中使用url获取文件大小

Question

我在网址中有一些图片。我可以获得文件属性，属性也包括图像的宽度和高度。我想以字节为单位获取大小。

我正在尝试使用 fs 模块获取大小，如下所示，但它不适用于 url，尽管它适用于本地文件夹中的文件路径。

var stats = fs.statSync(url);
var fileSizeInBytes = stats["size"]

Answer 1

您必须使用request, 或http。您可以通过发送HEAD请求和检查content-length字段来获取文件大小（它不适用于每个服务器）：

与curl：

curl -I "https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/core.js"

你得到回应：

HTTP/1.1 200 OK
Date: Tue, 03 Apr 2018 14:30:16 GMT
Content-Type: application/javascript; charset=utf-8
Content-Length: 9068
Connection: keep-alive
Last-Modified: Wed, 28 Feb 2018 04:16:30 GMT
ETag: "5a962d1e-236c"
Expires: Sun, 24 Mar 2019 14:30:16 GMT
Cache-Control: public, max-age=30672000
Access-Control-Allow-Origin: *
CF-Cache-Status: HIT
Accept-Ranges: bytes
Strict-Transport-Security: max-age=15780000; includeSubDomains
Expect-CT: max-age=604800, report-uri="https://report-uri.cloudflare.com/cdn-cgi/beacon/expect-ct"
Server: cloudflare
CF-RAY: 405c3b6e1911a8db-CDG

带request模块：

var request = require("request");

request({
    url: "https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/core.js",
    method: "HEAD"
}, function(err, response, body) {
    console.log(response.headers);
    process.exit(0);
});

你得到回应：

{
  date: 'Tue, 03 Apr 2018 14:29:32 GMT',
  'content-type': 'application/javascript; charset=utf-8',
  'content-length': '9068',
  connection: 'close',
  'last-modified': 'Wed, 28 Feb 2018 04:16:30 GMT',
  etag: '"5a962d1e-236c"',
  expires: 'Sun, 24 Mar 2019 14:29:32 GMT',
  'cache-control': 'public, max-age=30672000',
  'access-control-allow-origin': '*',
  'cf-cache-status': 'HIT',
  'accept-ranges': 'bytes',
  'strict-transport-security': 'max-age=15780000; includeSubDomains',
  'expect-ct': 'max-age=604800, report-uri="https://report-uri.cloudflare.com/cdn-cgi/beacon/expect-ct"',
  server: 'cloudflare',
  'cf-ray': '405c3a5cba7a68ba-CDG'
}