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.

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 }