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tshemsedinovtshemsedinov
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Add examples
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‎JavaScript/1-closure.js‎

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'use strict';
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const withContext = (context) => (accountId) => {
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const { console, rbac, user } = context;
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console.log(`User ${user.name} requesting balance for ${accountId}`);
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if (!rbac.check(user.role, 'read:balance')) {
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console.error('Access denied: insufficient permissions');
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return null;
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}
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const balance = 15420.5;
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console.log('Access granted');
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return balance;
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};
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// Usage
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const rbac = {
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permissions: {
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admin: ['read:balance', 'read:transactions', 'write:transactions'],
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user: ['read:balance'],
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guest: [],
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},
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check: (role, permission) => rbac.permissions[role]?.includes(permission),
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};
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const context = { console, rbac, user: { name: 'Marcus', role: 'admin' } };
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const getBalance = withContext(context);
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const balance = getBalance('Account-123');
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console.log(`Access granted: balance = $${balance}`);

‎JavaScript/2-oop.js‎

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'use strict';
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class AccountService {
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constructor(context) {
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this.context = context;
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}
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getBalance(accountId) {
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const { console, rbac, user } = this.context;
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console.log(`User ${user.name} requesting balance for ${accountId}`);
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if (!rbac.check(user.role, 'read:balance')) {
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console.error('Access denied: insufficient permissions');
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return null;
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}
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const balance = 15420.5;
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console.log('Access granted');
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return balance;
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}
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}
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// Usage
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class RBAC {
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constructor() {
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this.permissions = {
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admin: ['read:balance', 'read:transactions', 'write:transactions'],
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user: ['read:balance'],
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guest: [],
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};
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}
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check(role, permission) {
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return this.permissions[role]?.includes(permission);
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}
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}
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class User {
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constructor(name, role) {
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this.name = name;
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this.role = role;
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}
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}
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const rbac = new RBAC();
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const user = new User('Marcus', 'admin');
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const context = { console, rbac, user };
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const accountService = new AccountService(context);
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const balance = accountService.getBalance('Account-123');
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console.log(`Access granted: balance = $${balance}`);

‎JavaScript/3-factory.js‎

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'use strict';
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const createAccountService = (context) => {
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const { console, rbac, user } = context;
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const getBalance = (accountId) => {
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console.log(`User ${user.name} requesting balance for ${accountId}`);
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if (!rbac.check(user.role, 'read:balance')) {
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console.error('Access denied: insufficient permissions');
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return null;
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}
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return 15420.5;
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};
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const getTransactions = (accountId) => {
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if (!rbac.check(user.role, 'read:transactions')) {
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console.error('Access denied: insufficient permissions');
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return null;
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}
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console.log(`User ${user.name} reading transactions for ${accountId}`);
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return ['TR-123', 'TR-456', 'TR-789'];
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};
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return { getBalance, getTransactions };
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};
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// Usage
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const rbac = {
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permissions: {
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admin: ['read:balance', 'read:transactions', 'write:transactions'],
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user: ['read:balance'],
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guest: [],
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},
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check: (role, permission) => rbac.permissions[role]?.includes(permission),
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};
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const context = { console, rbac, user: { name: 'Marcus', role: 'admin' } };
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const accountService = createAccountService(context);
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console.log('Balance:', accountService.getBalance('ACC-001'));
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console.log('Transactions:', accountService.getTransactions('ACC-001'));

‎JavaScript/4-pipeline.js‎

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'use strict';
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const { randomUUID } = require('node:crypto');
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const generateRequestId = () => `req-${Date.now()}-${randomUUID()}`;
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const appendTrace = (context, step) => {
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const { trace = [] } = context;
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return [...trace, step];
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};
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const pipeline =
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(...steps) =>
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(context) => {
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const initial = Promise.resolve(context);
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const next = (chain, mw) => chain.then((ctx) => mw(ctx));
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return steps.reduce(next, initial);
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};
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const tracing = (context) => {
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const { console } = context;
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const next = {
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...context,
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requestId: context.requestId ?? generateRequestId(),
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trace: appendTrace(context, 'tracing'),
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};
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console.log(`[${next.requestId}] trace: ${next.trace.join(' -> ')}`);
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return Promise.resolve(next);
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};
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const auth = (context) => {
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const { console, headers } = context;
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const user = headers?.user ?? { name: 'anonymous', role: 'guest' };
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console.log(`[${context.requestId}] auth: ${user.name}`);
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return Promise.resolve({ ...context, user });
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};
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const rbac = (context) => {
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const permissions = {
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admin: ['read:balance', 'read:transactions'],
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user: ['read:balance'],
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guest: [],
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};
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const check = (role, permission) => permissions[role]?.includes(permission);
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return Promise.resolve({ ...context, rbac: { check, permissions } });
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};
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const getBalance = (context) => {
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const { console, rbac, user, requestId } = context;
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if (!rbac.check(user.role, 'read:balance')) {
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console.error(`[${requestId}] Access denied for ${user.name}`);
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return Promise.resolve({ ...context, status: 403, body: null });
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}
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console.log(`[${requestId}] Balance for ${user.name}`);
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const result = { ...context, status: 200, body: { balance: 15420.5 } };
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return Promise.resolve(result);
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};
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// Usage
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const execute = pipeline(tracing, auth, rbac, getBalance);
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const context = {
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console,
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headers: { user: { name: 'Marcus', role: 'admin' } },
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};
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execute(context).then((ctx) => {
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console.log('Response:', ctx.status, ctx.body);
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});

‎JavaScript/5-async.js‎

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'use strict';
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const { AsyncLocalStorage } = require('node:async_hooks');
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const asyncLocalStorage = new AsyncLocalStorage();
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const getBalance = async (accountId) => {
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const context = asyncLocalStorage.getStore();
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if (!context) throw new Error('No context');
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const { console, rbac, user, requestId } = context;
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console.log(`[${requestId}] User ${user.name} balance for ${accountId}`);
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if (!rbac.check(user.role, 'read:balance')) {
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console.error(`[${requestId}] Access denied for ${user.name}`);
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return null;
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}
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console.log(`[${requestId}] Balance for ${user.name}`);
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return Promise.resolve(15420.5);
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};
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// Usage
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const rbac = {
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permissions: {
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admin: ['read:balance'],
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user: ['read:balance'],
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guest: [],
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},
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check: (role, permission) => rbac.permissions[role]?.includes(permission),
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};
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const context = {
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console,
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rbac,
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user: { name: 'Marcus', role: 'admin' },
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requestId: 'req-001',
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};
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asyncLocalStorage.run(context, () => {
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console.log('Call: getBalance("ACC-001")');
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getBalance('ACC-002').then((result) => {
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console.log('Result:', result);
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});
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});

‎JavaScript/6-immutable.js‎

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'use strict';
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const createContext = (base, data = {}) => Object.freeze({ ...base, ...data });
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const withUser = (base, user) => createContext(base, { user });
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const withRequest = (base, requestId) => createContext(base, { requestId });
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const getBalance = (context, accountId) => {
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const { console, rbac, user, requestId } = context;
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if (!user) {
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console.error('No user in context');
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return null;
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}
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console.log(`Request ID: ${requestId}`);
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console.log(`User ${user.name} requesting balance for account ${accountId}`);
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if (!rbac.check(user.role, 'read:balance')) {
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console.error(`Access denied for ${user.name}`);
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return null;
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}
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return 15420.5;
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};
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// Usage
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const rbac = {
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permissions: {
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admin: ['read:balance'],
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user: ['read:balance'],
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guest: [],
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},
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check: (role, permission) => rbac.permissions[role]?.includes(permission),
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};
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const context1 = createContext({ console, rbac });
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console.log('Context 1:', getBalance(context1, 'ACC-002'), '\n');
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const context2 = withUser(context1, { name: 'Marcus', role: 'admin' });
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console.log('Context 2:', getBalance(context2, 'ACC-002'), '\n');
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const context3 = withRequest(context2, 'req-' + Date.now());
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console.log('Context 3:', getBalance(context3, 'ACC-002'), '\n');

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