如何手动设置 HTTP_X_FORWARDED_FOR 的值？

var xhr = new XMLHttpRequest();
xhr.open('GET', 'https://example.com/api', true);
xhr.setRequestHeader('X-Forwarded-For', '192.168.1.100');
xhr.send();

from flask import Flask, request

app = Flask(__name__)

@app.route('/api')
def api():
    headers = {'X-Forwarded-For': '192.168.1.100'}
    return 'Hello World', 200, headers

const express = require('express');
const app = express();

app.get('/api', (req, res) => {
  res.set('X-Forwarded-For', '192.168.1.100');
  res.send('Hello World');
});

app.listen(3000, () => {
  console.log('Server is running on port 3000');
});