Custom Errors in JavaScript

1// Method 1: Custom error class
2class CustomError extends Error {
3    constructor(message, code) {
4        super(message);
5        this.name = 'CustomError';
6        this.code = code;
7    }
8}
9
10try {
11    throw new CustomError('Something went wrong', 'ERR001');
12} catch (error) {
13    console.error('Custom error:', error.message);
14    console.error('Error code:', error.code);
15}
16
17// Method 2: Multiple custom errors
18class ValidationError extends Error {
19    constructor(message, field) {
20        super(message);
21        this.name = 'ValidationError';
22        this.field = field;
23    }
24}
25
26class NotFoundError extends Error {
27    constructor(resource) {
28        super(`${resource} not found`);
29        this.name = 'NotFoundError';
30        this.resource = resource;
31    }
32}
33
34try {
35    throw new ValidationError('Invalid email', 'email');
36} catch (error) {
37    if (error instanceof ValidationError) {
38        console.error('Validation error:', error.message, 'Field:', error.field);
39    }
40}
41
42// Method 3: Error factory
43function createError(type, message, details = {}) {
44    const error = new Error(message);
45    error.name = type;
46    Object.assign(error, details);
47    return error;
48}
49
50try {
51    throw createError('DatabaseError', 'Connection failed', { host: 'localhost', port: 5432 });
52} catch (error) {
53    console.error('Error:', error.name, error.message, error.host);
54}
55
56// Method 4: Error with stack trace
57class DetailedError extends Error {
58    constructor(message, context = {}) {
59        super(message);
60        this.name = 'DetailedError';
61        this.context = context;
62        this.timestamp = new Date().toISOString();
63    }
64    
65    toJSON() {
66        return {
67            name: this.name,
68            message: this.message,
69            context: this.context,
70            timestamp: this.timestamp,
71            stack: this.stack
72        };
73    }
74}
75
76const error = new DetailedError('Operation failed', { userId: 123, action: 'update' });
77console.log('Error JSON:', JSON.stringify(error, null, 2));