What are the main differences between AngularJS (1.x) and Angular, and is AngularJS still supported?
answer
- same team, different framework
- controllers and scope vs components
- digest loop vs view-tree check
- JavaScript vs TypeScript
- support ended early 2022
basics
~20 sAngularJS (1.x) is a JavaScript framework built on controllers, $scope and a digest loop of watchers; Angular is a TypeScript rewrite built on components, hierarchical dependency injection and top-down change detection. AngularJS support ended in January 2022.
solid answer
~50 sAngularJS is the name for all 1.x versions; Angular (2 and later) is a **complete rewrite**, not an upgrade path you can `npm update` across. AngularJS apps are built from **controllers** that put data on a **`$scope`**, **directives**, and string-named services, and it keeps the page in sync with a **digest cycle** that re-runs watchers until nothing changes. Angular is written in **TypeScript** and built from **components** with templates, services in **hierarchical injectors** resolved by type or token, and **change detection** that checks the component tree from the top down with one-way data flow. Templates changed too: `ng-*` attributes became `[property]` and `(event)` bindings and, today, `@if`/`@for` blocks. AngularJS reached **end of support in January 2022**, so it gets no security fixes; the `@angular/upgrade` package exists to run both side by side while you migrate.
go deeper
Recall the headline differences: TypeScript and components in Angular, controllers, $scope and the digest cycle in AngularJS, and that AngularJS support ended in January 2022.
Explain why the rewrite happened: digest cost, scope inheritance, string-based DI, and how one-way data flow and a single tree check address them.
Discuss what an unsupported AngularJS app means in production and which migration route fits a given codebase.
Weigh rewrite versus hybrid for a large AngularJS estate, including the cost of running two frameworks for months.
"AngularJS" and "Angular" share a team, a name and some vocabulary, which is exactly why interviewers ask how they differ. The short version: Angular is not a newer AngularJS, it is a different framework. ## Naming and status - **AngularJS** is the name for every **1.x** version. - **Angular** is everything from version 2 onwards; v22 is current in 2026. - **AngularJS reached end of support in January 2022.** It receives no fixes, including security fixes. - There is no in-place update from one to the other. The official route is a **hybrid app** with `@angular/upgrade`, which is itself in maintenance mode, taking only security fixes. ## The building blocks | Concern | AngularJS (1.x) | Angular | | :-- | :-- | :-- | | Language | JavaScript | TypeScript | | UI unit | Controllers plus templates, directives; `.component()` added later in 1.x | Components (a class with `@Component` and a template), directives, pipes | | Data for the view | Properties on a `$scope` object, often inherited from parent scopes | Fields and signals on the component class | | Data flow | Two-way binding by default (`ng-model` and directive bindings) | One-way by default: `[property]` in, `(event)` out; two-way is opt-in (`[(...)]`, `model()`) | | Keeping the view in sync | **Digest cycle**: re-run all watchers until values stop changing | **Change detection**: check the component tree top-down, then stop | | Dependency injection | Services looked up by string name; array annotations to survive minification | Hierarchical injectors; tokens are classes or `InjectionToken`s; `inject()` | | Modules | `angular.module('app', [...])` for registration | Standalone components by default since v19; `NgModule` still supported | | Templates | `ng-if`, `ng-repeat`, `ng-click`, `{{ }}` | `@if`, `@for`, `(click)`, `[prop]`, `{{ }}`, compiled ahead of time | ## Why the rewrite happened Three limits of AngularJS drove it: 1. **Performance of the digest cycle.** Every binding adds a watcher, and a digest runs all of them, repeatedly, until the page is stable. Large screens with thousands of bindings became slow, and two-way bindings could trigger cascades of extra passes. 2. **Scope inheritance was hard to reason about.** Nested `$scope`s inherited prototypally, so a child could read, shadow or accidentally write a parent's value. 3. **Tooling and scale.** String-named DI, runtime template compilation and plain JavaScript made large codebases hard to refactor and optimise. Angular answered with ahead-of-time compiled templates, TypeScript, one-way data flow, and a change-detection pass that walks the component tree once per cycle. ## What stayed recognisable - **Dependency injection** as the core design idea, now hierarchical and type-based. - **Declarative templates** with `{{ }}` interpolation. - **Directives** as a way to add behaviour to elements. - **Services** as singletons holding shared logic. This familiarity is why hybrid migrations work at all: the concepts map, even though the APIs do not. ## What interviewers listen for - Saying "Angular 2 was an upgrade of AngularJS" misses that it was a rewrite. - Describing Angular's change detection as "a digest loop" imports the AngularJS model: Angular checks the tree once, and in development mode a second verification pass throws `ExpressionChangedAfterItHasBeenCheckedError` (NG0100) instead of looping. - Treating AngularJS as merely "old but fine" ignores that since January 2022 it gets no security patches. ## Migration options in one line each - **Rewrite**: build the Angular app separately and switch over; clean, but a long freeze on the old app. - **Hybrid**: run both with `@angular/upgrade` and move one screen or service at a time. - **Replace gradually at the route level**: serve some routes from a new app; simpler plumbing, but two apps to operate. Which one fits depends on the app's size and test coverage; the hybrid route is the one Angular provides tools for.
- Can you update an AngularJS app to Angular with a package update?No. Angular is a rewrite with a different component model, change detection and DI, so there is no in-place update. The supported route is a hybrid app built with @angular/upgrade, where both frameworks run together and code moves over piece by piece, or a separate rewrite.
- Why does AngularJS need $scope.$apply() and Angular does not need an equivalent in most code?AngularJS only runs a digest when something inside its world triggers one, so changes from outside, such as a third-party callback, need $apply to start a digest. Angular schedules change detection itself, through zone.js in zone-based apps or through notifications such as signal writes, events and markForCheck in zoneless apps.
- What happens to security fixes for an app still on AngularJS today?There are none from the framework: AngularJS reached end of support in January 2022. Any newly found vulnerability stays unpatched unless the team patches or mitigates it itself, which is a strong argument for migrating or isolating the app.
saying these in an interview costs you the question
- Angular 2 was an incremental upgrade of AngularJS.
- Angular still uses a digest loop that repeats until values settle.
- Angular data binding is two-way by default, just like AngularJS.
- AngularJS is old but still receives security patches.
- Both frameworks resolve services by string name.