A complete modern Angular guide, from the CLI and components to signals, standalone APIs, SSR, state management, performance, testing, and production architecture.
Template-driven forms are Angular’s declarative approach to handling user input. Instead of building the form model in the component class, you define the structure and validation directly in the template using directives. The NgModel directive creates and manages the underlying FormControl instances, and two-way data binding with [(ngModel)] keeps the view and component model synchronized….
Angular provides a validation system built on the AbstractControl class, which FormControl, FormGroup, and FormArray all extend . Every validator is a function that receives a control and returns either null (valid) or a ValidationErrors object (invalid) . Built-in validators handle common cases — required, minLength, email, pattern — but real applications almost always need…
Simple forms have a fixed shape: a known set of fields, each present exactly once. Real applications rarely stay that simple. A survey builder lets users add and remove questions. An invoice editor has a list of line items, each with a description, quantity, and price. A settings panel has nested groups — server configuration…
Native HTML form elements — <input>, <select>, <textarea> — are integrated into Angular’s forms system through built-in directives called value accessors. When you write formControlName=”email” on an <input>, Angular’s DefaultValueAccessor handles the bridge between the DOM element and the FormControl instance. But the moment you need a control that is not an <input> — a…
Most front-end applications exist to communicate with a server. Fetching user data, submitting forms, loading configuration, uploading files — these are the operations that turn a static interface into a working application. Angular provides HttpClient for this purpose, a service built on the browser’s native fetch API (with XMLHttpRequest as an option) that wraps HTTP…
Every HTTP request an Angular application makes can pass through a series of functions that inspect it, modify it, or handle its response. These functions are interceptors. They are the mechanism for cross-cutting concerns — authentication, logging, error handling, caching, loading indicators, retry logic — that would otherwise be duplicated in every service method. Instead…
Errors are not exceptional. They are a normal part of every application that talks to a network, parses user input, or depends on code it does not control. A robust Angular application treats error handling as a design concern, not an afterthought. Errors appear at four distinct levels: within a component’s synchronous logic, within asynchronous…
Logging is the practice of recording what an application did. Observability is the broader discipline of understanding what an application is doing — through logs, metrics, traces, and the context that ties them together. In a front-end application, observability is often treated as an afterthought, because the developer’s console is right there and errors are…
RxJS is the reactive layer underneath Angular. Every HTTP call, every router event, every form value change, and every signal-based computation that Angular exposes is an Observable underneath. An Observable is a description of a stream — a sequence of values that arrive over time. Unlike a Promise, which produces exactly one value and resolves…
The previous chapter introduced Observables and the operator pipeline. This chapter goes deeper into the two largest categories of operators: transformation and filtering. Transformation operators change the values that flow through the stream — map converts each value, scan accumulates, switchMap and its siblings flatten inner Observables. Filtering operators decide which values continue — filter…