Types of Errors, Error Codes in JavaScript

JavaScript has several built-in error types that help in identifying and handling different kinds of errors. Here are some common error types:

SyntaxError

Occurs when there is a syntax issue in the code.

• Example:

    console.log('Hello; // Missing closing quote

ReferenceError

Occurs when a non-existent variable is referenced.

• Example:

    console.log(nonExistentVariable); // ReferenceError

TypeError

Occurs when a value is not of the expected type.

• Example:

    null.foo(); // TypeError: Cannot read property 'foo' of null

RangeError

Occurs when a value is not within the set or acceptable range.

• Example:

    new Array(-1); // RangeError: Invalid array length

EvalError

Occurs when the eval() function is used incorrectly. It's rarely encountered because eval() is discouraged.

• Example:

    eval('foo)'); // SyntaxError: Unexpected token

URIError

Occurs when there is an error in encoding or decoding URIs.

• Example:

    decodeURIComponent('%'); // URIError: URI malformed

Error Codes

Custom errors can be created with specific codes to handle specific conditions.

• Example:

    class CustomError extends Error {
      constructor(message, code) {
        super(message);
        this.code = code;
      }
    }

    throw new CustomError('Custom error message', 'E_CUSTOM');