stripe-middleware-3b.js

// ./middleware/billing.js

const billingApi = require('your-billing-package');

/**
 * Dont' allow payment below 1$
 */
function validateAmount(amount, source, description, currency) {
    if (amount < 1) {
        return Promise.reject('Payement not allowed. The minimum charge is 1.00$.');
    }
    return Promise.resolve();
}

/**
 * Only allow payement by Card
 */
function validateSource(amount, source) {
    if (source !== 'Card') {
        return Promise.reject('Only "Card" payement are allowed.')
    }
    return Promise.resolve();
}

// Add middleware to execute before any payement
// These are rules specific to this application
billingApi.pre('processPayement', [validateAmount, validateSource]);