# Developer Guides - [Modern Build Tools](https://docs.aurelia.io/developer-guides/bundlers.md): Modern build tool configuration for Aurelia 2, featuring Vite, Webpack, and Parcel with official plugins and optimal development experience. - [Component Library Development](https://docs.aurelia.io/developer-guides/component-library-development.md): Practical guide for creating reusable Aurelia 2 component libraries, covering architecture patterns, distribution strategies, and best practices without strong opinions. - [Advanced DI Patterns & Recipes](https://docs.aurelia.io/developer-guides/advanced-di-patterns.md) - [Security](https://docs.aurelia.io/developer-guides/security.md) - [Accessibility](https://docs.aurelia.io/developer-guides/accessibility.md) - [Debugging & Troubleshooting](https://docs.aurelia.io/developer-guides/debugging-and-troubleshooting.md): A comprehensive guide to debugging Aurelia 2 applications, troubleshooting common issues, and using development tools effectively. - [Testing](https://docs.aurelia.io/developer-guides/overview.md) - [Getting Started (Beginner Guide)](https://docs.aurelia.io/developer-guides/overview/testing-apps-and-components.md): A beginner-friendly guide to testing Aurelia applications and components - [Quick Reference ("How Do I...")](https://docs.aurelia.io/developer-guides/overview/testing.md) - [Decision Trees](https://docs.aurelia.io/developer-guides/overview/decision_trees.md) - [Testing components](https://docs.aurelia.io/developer-guides/overview/testing-components.md) - [Testing attributes](https://docs.aurelia.io/developer-guides/overview/testing-attributes.md) - [Testing value converters](https://docs.aurelia.io/developer-guides/overview/testing-value-converters.md) - [Working with the fluent API](https://docs.aurelia.io/developer-guides/overview/fluent-api.md) - [Stubs, mocks & spies](https://docs.aurelia.io/developer-guides/overview/mocks-spies.md) - [Advanced testing techniques](https://docs.aurelia.io/developer-guides/overview/advanced-testing.md) - [Outcome Recipes](https://docs.aurelia.io/developer-guides/overview/outcome-recipes.md): Advanced testing patterns for complex scenarios including async operations, routing, service mocking, and end-to-end component interaction testing. - [Developing with AI](https://docs.aurelia.io/developer-guides/developing-with-ai.md) - [Animation](https://docs.aurelia.io/developer-guides/animation.md): A comprehensive developer guide that details numerous strategies for implementing animations into Aurelia applications, including component-based animations, router transitions, and advanced animation - [Adding Animation (Beginner Guide)](https://docs.aurelia.io/developer-guides/animation/adding-animation.md): A beginner-friendly guide to adding animations to your Aurelia applications, starting with simple CSS animations and progressing to more dynamic techniques. - [Animation (Comprehensive Guide)](https://docs.aurelia.io/developer-guides/animation/animation.md): A comprehensive developer guide for implementing animations in Aurelia applications, covering CSS animations, Web Animations API, lifecycle hooks, third-party libraries, and advanced animation pattern - [Building plugins](https://docs.aurelia.io/developer-guides/building-plugins.md): Aurelia makes it easy to create your plugins. Learn how to create individual plugins, register them, and work with tasks to run code during certain parts of the lifecycle process. - [Working with Web Standards](https://docs.aurelia.io/developer-guides/working-with-web-standards.md) - [Web Components](https://docs.aurelia.io/developer-guides/web-components.md): The basics of the web-component plugin for Aurelia. - [UI virtualization](https://docs.aurelia.io/developer-guides/ui-virtualization.md) - [Performance optimization techniques](https://docs.aurelia.io/developer-guides/performance-optimization-techniques.md) - [Organizing large-scale projects](https://docs.aurelia.io/developer-guides/organizing-large-scale-projects.md) - [Error Handling Patterns](https://docs.aurelia.io/developer-guides/error-handling-patterns.md): Error handling and recovery patterns in Aurelia 2, including component error management, event handling, and user-friendly error recovery strategies. - [Third Party Library Integration](https://docs.aurelia.io/developer-guides/third-party-library-integration.md): Learn how to integrate third-party JavaScript libraries with Aurelia 2 using proper lifecycle management, DOM interaction patterns, and ref usage. - [Errors](https://docs.aurelia.io/developer-guides/error-messages.md) - [Kernel Errors](https://docs.aurelia.io/developer-guides/error-messages/0001-to-0023.md): Errors 0001 to 0023 are @aurelia/kernel package related errors. - [AUR0001](https://docs.aurelia.io/developer-guides/error-messages/0001-to-0023/aur0001.md): No registration for interface: xxxx - [AUR0002](https://docs.aurelia.io/developer-guides/error-messages/0001-to-0023/aur0002.md): Key was registered with a "none" resolver, are you injecting the right key? - [AUR0003](https://docs.aurelia.io/developer-guides/error-messages/0001-to-0023/aur0003.md): Cyclic dependency found: name - [AUR0004](https://docs.aurelia.io/developer-guides/error-messages/0001-to-0023/aur0004.md): Resolver for yyyy returned a null factory - [AUR0005](https://docs.aurelia.io/developer-guides/error-messages/0001-to-0023/aur0005.md): Invalid resolver strategy specified: yyyy - [AUR0006](https://docs.aurelia.io/developer-guides/error-messages/0001-to-0023/aur0006.md): Unable to autoregister dependency: \[yyyy] - [AUR0007](https://docs.aurelia.io/developer-guides/error-messages/0001-to-0023/aur0007.md): Resource key "yyyy" already registered - [AUR0008](https://docs.aurelia.io/developer-guides/error-messages/0001-to-0023/aur0008.md): Unable to resolve key: yyyy - [AUR0009](https://docs.aurelia.io/developer-guides/error-messages/0001-to-0023/aur0009.md): Attempted to jitRegister something that is not a constructor: 'yyyy'. Did you forget to register this resource? - [AUR0010](https://docs.aurelia.io/developer-guides/error-messages/0001-to-0023/aur0010.md): Attempted to jitRegister an intrinsic type: yyyy. Did you forget to add @inject(Key) - [AUR0011](https://docs.aurelia.io/developer-guides/error-messages/0001-to-0023/aur0011.md): Invalid resolver, null/undefined returned from the static register method. - [AUR0012](https://docs.aurelia.io/developer-guides/error-messages/0001-to-0023/aur0012.md): Attempted to jitRegister an interface: yyyy - [AUR0013](https://docs.aurelia.io/developer-guides/error-messages/0001-to-0023/aur0013.md): Cannot call resolve yyyy before calling prepare or after calling dispose. - [AUR0014](https://docs.aurelia.io/developer-guides/error-messages/0001-to-0023/aur0014.md): Key cannot be null or undefined. Are you trying to inject/register something that doesn't exist with DI? A common cause is circular dependency with bundler, did you accidentally introduce circular dep - [AUR0015](https://docs.aurelia.io/developer-guides/error-messages/0001-to-0023/aur0015.md): yyyy is a native function and, therefore cannot be safely constructed by DI. If this is intentional, please use a callback or cachedCallback resolver. - [AUR0016](https://docs.aurelia.io/developer-guides/error-messages/0001-to-0023/aur0016.md): There is not a currently active container to resolve "yyyy". Are you trying to "new Class(...)" that has a resolve(...) call? - [AUR0017](https://docs.aurelia.io/developer-guides/error-messages/0001-to-0023/aur0017.md): Failed to instantiate 'xxxx' via @newInstanceOf/@newInstanceForScope, there's no registration and no default implementation, or the default implementation does not result in factory for constructing t - [AUR0018](https://docs.aurelia.io/developer-guides/error-messages/0001-to-0023/aur0018.md): Invalid channel name or instance: 'yyyy'. - [AUR0019](https://docs.aurelia.io/developer-guides/error-messages/0001-to-0023/aur0019.md): Invalid channel name or type: yyyy. - [AUR0020](https://docs.aurelia.io/developer-guides/error-messages/0001-to-0023/aur0020.md): No defined value found when calling firstDefined() - [AUR0021](https://docs.aurelia.io/developer-guides/error-messages/0001-to-0023/aur0021.md): Invalid module transform input: yyyy. Expected Promise or Object. - [AUR0022](https://docs.aurelia.io/developer-guides/error-messages/0001-to-0023/aur0022.md): The @inject decorator on the target ('xxxx') type 'yyyy' is not supported. - [AUR0023](https://docs.aurelia.io/developer-guides/error-messages/0001-to-0023/aur0023.md): Resource key '{{0}}' has already been registered. - [Expression Parser Errors](https://docs.aurelia.io/developer-guides/error-messages/0151-to-0179.md): Errors 0151 to 0179 are @aurelia/expression-parser package related errors. - [AUR0099](https://docs.aurelia.io/developer-guides/error-messages/0151-to-0179/aur0099.md) - [AUR0101](https://docs.aurelia.io/developer-guides/error-messages/0151-to-0179/aur0101.md) - [AUR0102](https://docs.aurelia.io/developer-guides/error-messages/0151-to-0179/aur0102.md) - [AUR0103](https://docs.aurelia.io/developer-guides/error-messages/0151-to-0179/aur0103.md) - [AUR0105](https://docs.aurelia.io/developer-guides/error-messages/0151-to-0179/aur0105.md) - [AUR0106](https://docs.aurelia.io/developer-guides/error-messages/0151-to-0179/aur0106.md) - [AUR0107](https://docs.aurelia.io/developer-guides/error-messages/0151-to-0179/aur0107.md) - [AUR0108](https://docs.aurelia.io/developer-guides/error-messages/0151-to-0179/aur0108.md) - [AUR0109](https://docs.aurelia.io/developer-guides/error-messages/0151-to-0179/aur0109.md) - [AUR0110](https://docs.aurelia.io/developer-guides/error-messages/0151-to-0179/aur0110.md) - [AUR0111](https://docs.aurelia.io/developer-guides/error-messages/0151-to-0179/aur0111.md) - [AUR0112](https://docs.aurelia.io/developer-guides/error-messages/0151-to-0179/aur0112.md) - [AUR0151](https://docs.aurelia.io/developer-guides/error-messages/0151-to-0179/aur0151.md) - [AUR0152](https://docs.aurelia.io/developer-guides/error-messages/0151-to-0179/aur0152.md) - [AUR0153](https://docs.aurelia.io/developer-guides/error-messages/0151-to-0179/aur0153.md) - [AUR0154](https://docs.aurelia.io/developer-guides/error-messages/0151-to-0179/aur0154.md) - [AUR0155](https://docs.aurelia.io/developer-guides/error-messages/0151-to-0179/aur0155.md) - [AUR0156](https://docs.aurelia.io/developer-guides/error-messages/0151-to-0179/aur0156.md) - [AUR0157](https://docs.aurelia.io/developer-guides/error-messages/0151-to-0179/aur0157.md) - [AUR0158](https://docs.aurelia.io/developer-guides/error-messages/0151-to-0179/aur0158.md) - [AUR0159](https://docs.aurelia.io/developer-guides/error-messages/0151-to-0179/aur0159.md) - [AUR0160](https://docs.aurelia.io/developer-guides/error-messages/0151-to-0179/aur0160.md) - [AUR0161](https://docs.aurelia.io/developer-guides/error-messages/0151-to-0179/aur0161.md) - [AUR0162](https://docs.aurelia.io/developer-guides/error-messages/0151-to-0179/aur0162.md) - [AUR0163](https://docs.aurelia.io/developer-guides/error-messages/0151-to-0179/aur0163.md) - [AUR0164](https://docs.aurelia.io/developer-guides/error-messages/0151-to-0179/aur0164.md) - [AUR0165](https://docs.aurelia.io/developer-guides/error-messages/0151-to-0179/aur0165.md) - [AUR0166](https://docs.aurelia.io/developer-guides/error-messages/0151-to-0179/aur0166.md) - [AUR0167](https://docs.aurelia.io/developer-guides/error-messages/0151-to-0179/aur0167.md) - [AUR0168](https://docs.aurelia.io/developer-guides/error-messages/0151-to-0179/aur0168.md) - [AUR0170](https://docs.aurelia.io/developer-guides/error-messages/0151-to-0179/aur0170.md) - [AUR0171](https://docs.aurelia.io/developer-guides/error-messages/0151-to-0179/aur0171.md) - [AUR0172](https://docs.aurelia.io/developer-guides/error-messages/0151-to-0179/aur0172.md) - [AUR0173](https://docs.aurelia.io/developer-guides/error-messages/0151-to-0179/aur0173.md) - [AUR0174](https://docs.aurelia.io/developer-guides/error-messages/0151-to-0179/aur0174.md) - [AUR0175](https://docs.aurelia.io/developer-guides/error-messages/0151-to-0179/aur0175.md) - [AUR0176](https://docs.aurelia.io/developer-guides/error-messages/0151-to-0179/aur0176.md) - [AUR0178](https://docs.aurelia.io/developer-guides/error-messages/0151-to-0179/aur0178.md) - [AUR0179](https://docs.aurelia.io/developer-guides/error-messages/0151-to-0179/aur0179.md) - [Runtime Core Errors](https://docs.aurelia.io/developer-guides/error-messages/0203-to-0227.md): Errors 0199 to 0228 are @aurelia/runtime package related errors. - [AUR0099](https://docs.aurelia.io/developer-guides/error-messages/0203-to-0227/aur0099.md) - [AUR0199](https://docs.aurelia.io/developer-guides/error-messages/0203-to-0227/aur0199.md) - [AUR0203](https://docs.aurelia.io/developer-guides/error-messages/0203-to-0227/aur0203.md) - [AUR0204](https://docs.aurelia.io/developer-guides/error-messages/0203-to-0227/aur0204.md) - [AUR0206](https://docs.aurelia.io/developer-guides/error-messages/0203-to-0227/aur0206.md) - [AUR0207](https://docs.aurelia.io/developer-guides/error-messages/0203-to-0227/aur0207.md) - [AUR0208](https://docs.aurelia.io/developer-guides/error-messages/0203-to-0227/aur0208.md) - [AUR0209](https://docs.aurelia.io/developer-guides/error-messages/0203-to-0227/aur0209.md) - [AUR0210](https://docs.aurelia.io/developer-guides/error-messages/0203-to-0227/aur0210.md) - [AUR0217](https://docs.aurelia.io/developer-guides/error-messages/0203-to-0227/aur0217.md) - [AUR0218](https://docs.aurelia.io/developer-guides/error-messages/0203-to-0227/aur0218.md) - [AUR0219](https://docs.aurelia.io/developer-guides/error-messages/0203-to-0227/aur0219.md) - [AUR0220](https://docs.aurelia.io/developer-guides/error-messages/0203-to-0227/aur0220.md) - [AUR0221](https://docs.aurelia.io/developer-guides/error-messages/0203-to-0227/aur0221.md) - [AUR0224](https://docs.aurelia.io/developer-guides/error-messages/0203-to-0227/aur0224.md) - [AUR0225](https://docs.aurelia.io/developer-guides/error-messages/0203-to-0227/aur0225.md) - [AUR0226](https://docs.aurelia.io/developer-guides/error-messages/0203-to-0227/aur0226.md) - [AUR0227](https://docs.aurelia.io/developer-guides/error-messages/0203-to-0227/aur0227.md) - [AUR0228](https://docs.aurelia.io/developer-guides/error-messages/0203-to-0227/aur0228.md) - [Template Compiler Errors](https://docs.aurelia.io/developer-guides/error-messages/0088-to-0723.md): Errors 0088 to 0723 are @aurelia/template-compiler package related errors. - [AUR0088](https://docs.aurelia.io/developer-guides/error-messages/0088-to-0723/aur0088.md): AttributeParser is already initialized; cannot add patterns after initialization. - [AUR0089](https://docs.aurelia.io/developer-guides/error-messages/0088-to-0723/aur0089.md): Attribute pattern "yyyy" has already been registered. - [AUR0099](https://docs.aurelia.io/developer-guides/error-messages/0088-to-0723/aur0099.md) - [AUR0157](https://docs.aurelia.io/developer-guides/error-messages/0088-to-0723/aur0157.md): Binding command {{0}} has already been registered. - [AUR0701](https://docs.aurelia.io/developer-guides/error-messages/0088-to-0723/aur0701.md): Template compilation error in element "{{0:name}}": the root \