Error Types

JavaScript has many built-in error types, and you can create custom errors too.

🚨 Error Types:

• Error: Generic error

• SyntaxError: Invalid syntax

• ReferenceError: Invalid reference

• TypeError: Wrong type

• RangeError: Number out of range

javascript

// Different error types
function demonstrateErrors() {
    // 1. ReferenceError
    try {
        console.log(undefinedVariable);
    } catch (e) {
        console.log(`${e.name}: ${e.message}`);
    }
    
    // 2. TypeError
    try {
        null.toString();
    } catch (e) {
        console.log(`${e.name}: ${e.message}`);
    }
    
    // 3. RangeError
    try {
        const arr = new Array(-1);
    } catch (e) {
        console.log(`${e.name}: Invalid array length`);
    }
}

demonstrateErrors();

// Custom Error
class ValidationError extends Error {
    constructor(message) {
        super(message);
        this.name = "ValidationError";
    }
}

function validateAge(age) {
    if (age < 0 || age > 120) {
        throw new ValidationError("Age must be between 0 and 120");
    }
    return `Valid age: ${age}`;
}

try {
    console.log(validateAge(25));
    console.log(validateAge(150));
} catch (error) {
    console.log(`${error.name}: ${error.message}`);
}

You should see

ReferenceError: undefinedVariable is not defined TypeError: Cannot read properties of null RangeError: Invalid array length Valid age: 25 ValidationError: Age must be between 0 and 120