JavaScript Error_custom Guide
Create custom error types, extend Error class, and implement structured error handling for robust applications. The guide walks through Custom Errors. `class ValidationError extends Error { constructor(msg, field) { super(msg); this.name = "ValidationError"; this.field = field } }`. Include: error name, message, stack, context data (field, value, timestamp). Check type: `if (err instanceof ValidationError)`. Throw meaningful errors in your code. Catch at the boundary (UI, API) and format for the user. The guide is organized into 1 sections that build on each other, each pairing a prose explanation with runnable code. Related guides: Arrays, Strings, Numbers, Math, Date. This is one of 145 JavaScript guides on JS Reference — see the full list on the guides page. Practice what you learn in the JavaScript playground, and look up any unfamiliar term in the JavaScript glossary.