JavaScript Random String Generator

Common JavaScript Code Examples

function generateRandomString(length) {
  const chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789';
  const arr = new Uint8Array(length);
  window.crypto.getRandomValues(arr);
  return Array.from(arr).map(b => chars[b % chars.length]).join('');
}

const { randomBytes } = require('crypto');
function nodeRandomString(length) {
  const chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789';
  return Array.from(randomBytes(length)).map(b => chars[b % chars.length]).join('');
}

import { useState } from 'react';
function useRandomString(length) {
  const [value, setValue] = useState('');
  const generate = () => {
    const chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789';
    const arr = new Uint8Array(length);
    window.crypto.getRandomValues(arr);
    setValue(Array.from(arr).map(b => chars[b % chars.length]).join(''));
  };
  return [value, generate];
}

FAQ & Technical Docs

• Q: Why not use Math.random() for passwords or API keys?
  Math.random() is not cryptographically secure and can be predicted. For passwords, API keys, and other sensitive data, always use crypto.getRandomValues() (browser) or crypto.randomBytes (Node.js) for true security.
• Q: How to ensure the generated strings are unique?
  Random strings generated with secure algorithms have a very low probability of collision. For absolute uniqueness, you can add a timestamp, user ID, or perform a database check.
• Q: Can I use a custom character set?
  Yes. Enter any characters in the "Custom Charset" field and combine with other types as needed to fit your requirements.
• Q: What algorithm does this tool use?
  This tool uses cryptographically secure pseudo-random number generators (CSPRNG), such as browser crypto.getRandomValues() and Node.js crypto.randomBytes, to ensure high security and unpredictability.