Cross-Site Scripting (XSS) is a type of security vulnerability that occurs when an attacker can inject malicious scripts into the web page being viewed by another user. To mitigate this risk, here are some steps to solve XSS issues in Node.js:

1. Input Validation and Escaping: Input validation should be performed on all incoming data before it is inserted into your database or rendered on a webpage. This helps prevent malicious scripts from entering the system. Use libraries like Joi for input validation and escape the output using ejs templating language, escape-html, or he.

const express = require('express');
const app = express();
const ejs = require('ejs');
app.set('view engine', 'ejs');

// Example of input validation using Joi
const Joi = require('joi');
const schema = Joi.object({
  name: Joi.string().alphanum().min(3).max(30),
});

app.post('/', (req, res) => {
  try {
    // Validate input
    const { error } = schema.validate(req.body);
    if (error) {
      return res.status(400).send(error.details[0].message);
    }

    res.send(`Welcome, ${req.body.name}`);
  } catch (err) {
    console.log(err);
    res.status(500).send('Internal Server Error');
  }
});

2. Use Content Security Policy (CSP): CSP is a web application security feature that helps prevent XSS attacks by restricting the types of resources that can be loaded on a page. Set Content-Security-Policy header in your server responses to specify allowed sources for scripts, stylesheets, images, etc.

app.use((req, res, next) => {
  res.setHeader('Content-Security-Policy', "script-src 'self'");
  next();
});

3. Use HTTPOnly and Secure flags: When storing sensitive data in cookies or session storage, use the HttpOnly flag to prevent client-side scripts from accessing it, and the Secure flag to make sure that only HTTPS connections are used.

4. Sanitize output: Use libraries like dompurify or sanitize-html to sanitize any user-generated content before rendering it on a webpage. This will prevent malicious scripts from being executed.

const sanitizeHtml = require('sanitize-html');

app.get('/', (req, res) => {
  const userInput = '<b>Hello</b> World';
  const sanitizedOutput = sanitizeHtml(userInput);
  res.send(`<p>${sanitizedOutput}</p>`);
});

5. Use X-XSS-Protection header: Set X-XSS-Protection header to tell the browser to enable XSS filtering. This will help prevent some types of XSS attacks.

app.use((req, res, next) => {
  res.setHeader('X-XSS-Protection', '1; mode=block');
  next();
});

6. Regularly update libraries and dependencies: Keep all your Node.js packages up to date with the latest security patches. Libraries like Express, Joi, SanitizeHtml etc., have their own built-in security features that can help prevent XSS attacks.

7. Use secure session management: Use a library like express-session or cookie-parser to manage user sessions and make sure that sessions are HTTPS only.

Remember, there is no one-size-fits-all solution for XSS prevention. Always review your application thoroughly and identify potential vulnerabilities before implementing any security measures.