cap/docs/guide/server.md

@cap.js/server

@cap.js/server is Cap's server-side library. It helps you create and validate challenges for your users. Start by installing it using npm or bun:

npm i @cap.js/server

Note

It is recommended to use at least Node.js 14 or Bun 1.0.0. You might experience multiple issues on older versions of these runtimes.
If you're using Glitch, make sure to set node 14 or higher in your engines field in package.json

Example code

const express = require('express');
const Cap = require('@cap.js/server');

const app = express();
app.use(express.json());

const cap = new Cap({
  tokens_store_path: '.data/tokensList.json' // make sure this file has already been created and added to your gitignore
});

app.post('/api/challenge', (req, res) => {
  res.json(cap.createChallenge());
});

app.post('/api/redeem', async (req, res) => {
  const { token, solutions } = req.body;
  if (!token || !solutions) {
    return res.status(400).json({ success: false });
  }
  res.json(await cap.redeemChallenge({ token, solutions }));
});

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

Supported methods and arguments

The following methods are supported:

new Cap({ ... })

Creates a new Cap instance.

Arguments

{
  tokens_store_path: ".data/tokensList.json",
  state: {
    challengesList: {},
    tokensList: {},
  },
}

Tip

You can always access or set the options of the Cap class by accessing or modifying the cap.config object.

cap.createChallenge({ ... })

Arguments

{
  challengeCount: 18,
  challengeSize: 32,
  challengeDifficulty: 4,
  expiresMs: 600000
}

Output: { challenge, expires }

cap.redeemChallenge({ ... })

{
  token,
  solutions
}

Output: { success, token }

await cap.validateToken("...", { ... })

Arguments:

{
  keepToken: false
}

Output: { success }