@angular/common

What is @angular/common?

The @angular/common package is a core Angular library that provides commonly needed services, pipes, and directives that are essential for application development. It is part of the Angular framework and is used for tasks such as HTTP communication, localization, and various utility functions.

What are @angular/common's main functionalities?

HTTP Client

Provides a simplified API for HTTP functionality which allows performing HTTP requests and handling responses within an Angular application.

import { HttpClientModule } from '@angular/common/http';

@NgModule({
  imports: [
    HttpClientModule
  ]
})
export class AppModule { }

Common Directives

Includes directives like ngIf, ngFor, and ngSwitch which are essential for controlling the rendering of the template.

import { CommonModule } from '@angular/common';

@NgModule({
  imports: [
    CommonModule
  ]
})
export class SharedModule { }

Location Services

Provides services for interacting with the browser's URL. Useful for routing and navigation within an Angular application.

import { Location } from '@angular/common';

@Component({
  selector: 'app-component',
  template: '<p>Current path: {{ location.path() }}</p>'
})
export class AppComponent {
  constructor(public location: Location) { }
}

Date, Currency, and Decimal Pipes

Provides built-in pipes for formatting data such as dates, currency, and numbers.

import { DatePipe, CurrencyPipe, DecimalPipe } from '@angular/common';

@Component({
  selector: 'app-component',
  template: '<p>Today is {{ today | date }}</p><p>Amount: {{ amount | currency }}</p>'
})
export class AppComponent {
  today = new Date();
  amount = 1234.56;
}

Other packages similar to @angular/common

react

React is a JavaScript library for building user interfaces. While it is not a one-to-one comparison with @angular/common, React provides a component-based architecture similar to Angular's directives and services.

vue

Vue.js is a progressive JavaScript framework used for building UIs and single-page applications. It offers similar directives and reactivity systems but is generally considered to be more lightweight and easier to integrate into projects than Angular.

axios

Axios is a promise-based HTTP client for the browser and Node.js. It provides many of the same HTTP client capabilities as the HttpClientModule in @angular/common.

moment

Moment.js is a library for parsing, validating, manipulating, and formatting dates. It is similar to the DatePipe in @angular/common but is a standalone library focused solely on date manipulation.

README

Angular

The sources for this package are in the main Angular repo. Please file issues and pull requests against that repo.

License: MIT

Changelog

14.0.0 (2022-06-02)

Blog post "Angular v14 is now available".

Breaking Changes

animations

• The AnimationDriver.getParentElement method has become required, so any implementors of this interface are now required to provide an implementation for this method. This breakage is unlikely to affect application developers, as AnimationDriver is not expected to be implemented in user code.

common

• Adds new required class member that any implementors of the LocationStrategy will need to satisfy. Location does not depend on PlatformLocation anymore.

compiler

• Keyframes names are now prefixed with the component's "scope name". For example, the following keyframes rule in a component definition, whose "scope name" is host-my-cmp:

  @keyframes foo { ... }

  will become:

  @keyframes host-my-cmp_foo { ... }

  Any TypeScript/JavaScript code which relied on the names of keyframes rules will no longer match.

  The recommended solutions in this case are to either:

  • change the component's view encapsulation to the None or ShadowDom
  • define keyframes rules in global stylesheets (e.g styles.css)
  • define keyframes rules programmatically in code.

core

• Support for Node.js v12 has been removed as it will become EOL on 2022-04-30. Please use Node.js v14.15 or later.

• TypeScript versions older than 4.6 are no longer supported.

• Forms [email] input coercion

  Forms [email] input value will be considered as true if it is defined with any value rather than false and 'false'.

• Since Ivy, TestBed doesn't use AOT summaries. The aotSummaries fields in TestBed APIs were present, but unused. The fields were deprecated in previous major version and in v14 those fields are removed. The aotSummaries fields were completely unused, so you can just drop them from the TestBed APIs usage.

forms

• Forms classes accept a generic.

  Forms model classes now accept a generic type parameter. Untyped versions of these classes are available to opt-out of the new, stricter behavior.

• objects with a length key set to zero will no longer validate as empty.

  This is technically a breaking change, since objects with a key length and value 0 will no longer validate as empty. This is a very minor change, and any reliance on this behavior is probably a bug anyway.

http

• Queries including + will now actually query for + instead of space. Most workarounds involving custom codecs will be unaffected. Possible server-side workarounds will need to be undone.

• JSONP will throw an error when headers are set on a reques

  JSONP does not support headers being set on requests. Before when a request was sent to a JSONP backend that had headers set the headers were ignored. The JSONP backend will now throw an error if it receives a request that has any headers set. Any uses of JSONP on requests with headers set will need to remove the headers to avoid the error.

platform-browser

• This change may cause a breaking change in unit tests that are implicitly depending on a specific number and sequence of change detections in order for their assertions to pass.

• This may break invalid calls to TransferState methods.

  This tightens parameter types of TransferState usage, and is a minor breaking change which may reveal existing problematic calls.

router

• The type of Route.pathMatch is now stricter. Places that use pathMatch will likely need to be updated to have an explicit Route/Routes type so that TypeScript does not infer the type as string.
• When returning a Promise from the LoadChildrenCallback, the possible type is now restricted to Type<any>|NgModuleFactory<any> rather than any.
• initialNavigation: 'enabled' was deprecated in v11 and is replaced by initialNavigation: 'enabledBlocking'.
• The type of component on ActivatedRoute and ActivatedRouteSnapshot includes string. In reality, this is not the case. The component cannot be anything other than a component class.
• • The type of initialUrl is set to string|UrlTree but in reality, the Router only sets it to a value that will always be UrlTree
  • initialUrl is documented as "The target URL passed into the Router#navigateByUrl() call before navigation" but the value actually gets set to something completely different. It's set to the current internal UrlTree of the Router at the time navigation occurs.
  With this change, there is no exact replacement for the old value of initialUrl because it was never intended to be exposed. Router.url is likely the best replacement for this. In more specific use-cases, tracking the finalUrl between successful navigations can also be used as a replacement.
• Lazy loaded configs are now also validated once loaded like the initial set of routes are. Lazy loaded modules which have invalid Route configs will now error. Note that this is only done in dev mode so there is no production impact of this change.
• When a guard returns a UrlTree, the router would previously schedule the redirect navigation within a setTimeout. This timeout is now removed, which can result in test failures due to incorrectly written tests. Tests which perform navigations should ensure that all timeouts are flushed before making assertions. Tests should ensure they are capable of handling all redirects from the original navigation.
• Previously, resolvers were waiting to be completed before proceeding with the navigation and the Router would take the last value emitted from the resolver. The router now takes only the first emitted value by the resolvers and then proceeds with navigation. This is now consistent with Observables returned by other guards: only the first value is used.