Context/JavaScript/6-immutable.js at main · HowProgrammingWorks/Context · GitHub

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'use strict';

const createContext = (base, data = {}) =>

Object.freeze({ ...base, ...data });

const withUser = (base, user) => createContext(base, { user });

const withRequest = (base, requestId) => createContext(base, { requestId });

const getBalance = (context, accountId) => {

const { console, accessPolicy, user, requestId } = context;

if (!user) {

console.error('No user in context');

return null;

}

console.log(`Request ID: ${requestId}`);

console.log(`User ${user.name} requesting balance for account ${accountId}`);

if (!accessPolicy.check(user.role, 'read:balance')) {

console.error(`Access denied for ${user.name}`);

return null;

}

return 15420.5;

};

// Usage

const accessPolicy = {

permissions: {

admin: ['read:balance'],

user: ['read:balance'],

guest: [],

},

check: (role, permission) =>

accessPolicy.permissions[role]?.includes(permission),

};

const context1 = createContext({ console, accessPolicy });

console.log('Context 1:', getBalance(context1, 'ACC-002'), '\n');

const context2 = withUser(context1, { name: 'Marcus', role: 'admin' });

console.log('Context 2:', getBalance(context2, 'ACC-002'), '\n');

const context3 = withRequest(context2, `req-${Date.now()}`);

console.log('Context 3:', getBalance(context3, 'ACC-002'), '\n');