Angular Signals under the Hood

Dive deep into the inner workings of Angular signals with 'Angular Signals under the Hood'. This talk offers an in-depth exploration of Angular signals, uncovering the mechanics and nuances that power this advanced feature. We'll dissect the core concepts, architecture, and how signals enhance communication and performance in Angular applications. Ideal for developers seeking a thorough understanding of Angular signals, this presentation will provide you with the knowledge to leverage these tools effectively in your projects, ensuring optimized and future-proof Angular applications.

2. What are Signals?
3. const todos = signal([]);
4. todos = signal<Todo[]>([]); todos(); todos.set(...); todos.update((items) => { /* ... */ }); 1 2 3 4 5 6 7
5. todos = signal<Todo[]>([]); todos(); todos.set(...); todos.update((items) => { /* ... */ }); 1 2 3 4 5 6 7 todos = signal<Todo[]>([]); 1 2 todos(); 3 4 todos.set(...); 5 6 todos.update((items) => { /* ... */ }); 7
6. todos = signal<Todo[]>([]); todos(); todos.set(...); todos.update((items) => { /* ... */ }); 1 2 3 4 5 6 7 todos = signal<Todo[]>([]); 1 2 todos(); 3 4 todos.set(...); 5 6 todos.update((items) => { /* ... */ }); 7 todos(); todos = signal<Todo[]>([]); 1 2 3 4 todos.set(...); 5 6 todos.update((items) => { /* ... */ }); 7
7. todos = signal<Todo[]>([]); todos(); todos.set(...); todos.update((items) => { /* ... */ }); 1 2 3 4 5 6 7 todos = signal<Todo[]>([]); 1 2 todos(); 3 4 todos.set(...); 5 6 todos.update((items) => { /* ... */ }); 7 todos(); todos = signal<Todo[]>([]); 1 2 3 4 todos.set(...); 5 6 todos.update((items) => { /* ... */ }); 7 todos.set(...); todos = signal<Todo[]>([]); 1 2 todos(); 3 4 5 6 todos.update((items) => { /* ... */ }); 7
8. todos = signal<Todo[]>([]); todos(); todos.set(...); todos.update((items) => { /* ... */ }); 1 2 3 4 5 6 7 todos = signal<Todo[]>([]); 1 2 todos(); 3 4 todos.set(...); 5 6 todos.update((items) => { /* ... */ }); 7 todos(); todos = signal<Todo[]>([]); 1 2 3 4 todos.set(...); 5 6 todos.update((items) => { /* ... */ }); 7 todos.set(...); todos = signal<Todo[]>([]); 1 2 todos(); 3 4 5 6 todos.update((items) => { /* ... */ }); 7 todos.update((items) => { /* ... */ }); todos = signal<Todo[]>([]); 1 2 todos(); 3 4 todos.set(...); 5 6 7
9. todos = signal<Todo[]>([]); count = computed(() => todos().length); effect(() => { console.log('Todos count changed to ', count()); }); 1 2 3 4 5 6 7
10. todos = signal<Todo[]>([]); count = computed(() => todos().length); effect(() => { console.log('Todos count changed to ', count()); }); 1 2 3 4 5 6 7 count = computed(() => todos().length); todos = signal<Todo[]>([]); 1 2 3 4 effect(() => { 5 console.log('Todos count changed to ', count()); 6 }); 7
11. todos = signal<Todo[]>([]); count = computed(() => todos().length); effect(() => { console.log('Todos count changed to ', count()); }); 1 2 3 4 5 6 7 count = computed(() => todos().length); todos = signal<Todo[]>([]); 1 2 3 4 effect(() => { 5 console.log('Todos count changed to ', count()); 6 }); 7 effect(() => { console.log('Todos count changed to ', count()); }); todos = signal<Todo[]>([]); 1 2 count = computed(() => todos().length); 3 4 5 6 7
12. todos = signal<Todo[]>([]); console.log('Todos: ' + todos()); effect(() => { console.log('Todos', todos()); }); 1 2 3 4 5 6 7
13. todos = signal<Todo[]>([]); console.log('Todos: ' + todos()); effect(() => { console.log('Todos', todos()); }); 1 2 3 4 5 6 7 console.log('Todos: ' + todos()); todos = signal<Todo[]>([]); 1 2 3 4 effect(() => { 5 console.log('Todos', todos()); 6 }); 7
14. todos = signal<Todo[]>([]); console.log('Todos: ' + todos()); effect(() => { console.log('Todos', todos()); }); 1 2 3 4 5 6 7 console.log('Todos: ' + todos()); todos = signal<Todo[]>([]); 1 2 3 4 effect(() => { 5 console.log('Todos', todos()); 6 }); 7 effect(() => { console.log('Todos', todos()); }); todos = signal<Todo[]>([]); 1 2 console.log('Todos: ' + todos()); 3 4 5 6 7
16. console.log('Todos: ' + todos()); todos = signal<Todo[]>([]); 1 2 3 4 effect(() => { 5 console.log('Todos', todos()); 6 }); 7
17. console.log('Todos: ' + todos()); todos = signal<Todo[]>([]); 1 2 3 4 effect(() => { 5 console.log('Todos', todos()); 6 }); 7 effect(() => { console.log('Todos', todos()); }); todos = signal<Todo[]>([]); 1 2 console.log('Todos: ' + todos()); 3 4 5 6 7
18. Reactivity
19. Reactivity Context base o
20. // Reactive in TS effect(() => { console.log('Todos', todos()); }); // Reactive in HTML <div>{{ todos() }}</div> todos = signal<Todo[]>([]); 1 2 console.log('Todos: ' + todos()); 3 4 5 6 7 8 9 10 11
21. Live Consumers
22. Consumers
23. Consumers Producers
24. Consumers Producers Or Both!
25. Reactive Graph
26. https://github.com/angular/angular/blob/17.1.2/packages/core/primitives/signals/src/graph.ts#L36-L44
27. todos = signal<Todo[]>([]); effect(() => { console.log('Todos', todos()); }); 1 2 3 4 5
28. Signal Reactive Context
29. Signal Reactive Context todos() effect() / HTML
30. Signal todos() Reactive Context effect() / HTML
31. Signal todos() Reactive Context effect() / HTML
32. Push Pull
33. /** * Propagate a dirty notification to live consumers of this producer. */ export function producerNotifyConsumers(node: ReactiveNode): void { if (node.liveConsumerNode === undefined) { return; } // Prevent signal reads when we're updating the graph const prev = inNotificationPhase; inNotificationPhase = true; try { for (const consumer of node.liveConsumerNode) { if (!consumer.dirty) { consumerMarkDirty(consumer); } } } finally { inNotificationPhase = prev; } } 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21
34. /** * Propagate a dirty notification to live consumers of this producer. */ export function producerNotifyConsumers(node: ReactiveNode): void { if (node.liveConsumerNode === undefined) { return; } // Prevent signal reads when we're updating the graph const prev = inNotificationPhase; inNotificationPhase = true; try { for (const consumer of node.liveConsumerNode) { if (!consumer.dirty) { consumerMarkDirty(consumer); } } } finally { inNotificationPhase = prev; } } 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 export function producerNotifyConsumers(node: ReactiveNode): void { /** 1 * Propagate a dirty notification to live consumers of this producer. 2 */ 3 4 if (node.liveConsumerNode === undefined) { 5 return; 6 } 7 8 // Prevent signal reads when we're updating the graph 9 const prev = inNotificationPhase; 10 inNotificationPhase = true; 11 try { 12 for (const consumer of node.liveConsumerNode) { 13 if (!consumer.dirty) { 14 consumerMarkDirty(consumer); 15 } 16 } 17 } finally { 18 inNotificationPhase = prev; 19 } 20 } 21
35. /** * Propagate a dirty notification to live consumers of this producer. */ export function producerNotifyConsumers(node: ReactiveNode): void { if (node.liveConsumerNode === undefined) { return; } // Prevent signal reads when we're updating the graph const prev = inNotificationPhase; inNotificationPhase = true; try { for (const consumer of node.liveConsumerNode) { if (!consumer.dirty) { consumerMarkDirty(consumer); } } } finally { inNotificationPhase = prev; } } 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 export function producerNotifyConsumers(node: ReactiveNode): void { /** 1 * Propagate a dirty notification to live consumers of this producer. 2 */ 3 4 if (node.liveConsumerNode === undefined) { 5 return; 6 } 7 8 // Prevent signal reads when we're updating the graph 9 const prev = inNotificationPhase; 10 inNotificationPhase = true; 11 try { 12 for (const consumer of node.liveConsumerNode) { 13 if (!consumer.dirty) { 14 consumerMarkDirty(consumer); 15 } 16 } 17 } finally { 18 inNotificationPhase = prev; 19 } 20 } 21 consumerMarkDirty(consumer); /** 1 * Propagate a dirty notification to live consumers of this producer. 2 */ 3 export function producerNotifyConsumers(node: ReactiveNode): void { 4 if (node.liveConsumerNode === undefined) { 5 return; 6 } 7 8 // Prevent signal reads when we're updating the graph 9 const prev = inNotificationPhase; 10 inNotificationPhase = true; 11 try { 12 for (const consumer of node.liveConsumerNode) { 13 if (!consumer.dirty) { 14 15 } 16 } 17 } finally { 18 inNotificationPhase = prev; 19 } 20 } 21
36. todos = signal<Todo[]>([]); effect(() => { console.log('Todos', todos()); }); 1 2 3 4 5
37. todos = signal<Todo[]>([]); effect(() => { if(false) { console.log('Todos', todos()); } }); 1 2 3 4 5 6 7
38. Live Consumers
39. count = computed(() => todos().length); effect(() => { console.log('Todos count changed to ', count()); }); todos = signal<Todo[]>([]); 1 2 3 4 5 6 7
40. count = computed(() => todos().length); effect(() => { console.log('just a message'); }); todos = signal<Todo[]>([]); 1 2 3 4 5 6 7
41. Live Consumers Transitive
42. Signal todos() Reactive Context effect() / HTML computed()
43. Signal todos() Reactive Context effect() / HTML computed()
44. Signal todos() Reactive Context effect() / HTML computed()
45. Signal todos() Reactive Context effect() / HTML computed()
46. Signal todos() Reactive Context effect() / HTML computed()
47. Versioning
48. interface ConsumerNode extends ReactiveNode interface ProducerNode extends ReactiveNode export interface ReactiveNode { version: Version; lastCleanEpoch: Version; dirty: boolean; producerNode: ReactiveNode[] | undefined; producerLastReadVersion: Version[] | undefined; producerIndexOfThis: number[] | undefined; nextProducerIndex: number; liveConsumerNode: ReactiveNode[] | undefined; liveConsumerIndexOfThis: number[] | undefined; consumerAllowSignalWrites: boolean; readonly consumerIsAlwaysLive: boolean; producerMustRecompute(node: unknown): boolean; producerRecomputeValue(node: unknown): void; consumerMarkedDirty(node: unknown): void; consumerOnSignalRead(node: unknown): void; } 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21
49. interface ConsumerNode extends ReactiveNode interface ProducerNode extends ReactiveNode export interface ReactiveNode { version: Version; lastCleanEpoch: Version; dirty: boolean; producerNode: ReactiveNode[] | undefined; producerLastReadVersion: Version[] | undefined; producerIndexOfThis: number[] | undefined; nextProducerIndex: number; liveConsumerNode: ReactiveNode[] | undefined; liveConsumerIndexOfThis: number[] | undefined; consumerAllowSignalWrites: boolean; readonly consumerIsAlwaysLive: boolean; producerMustRecompute(node: unknown): boolean; producerRecomputeValue(node: unknown): void; consumerMarkedDirty(node: unknown): void; consumerOnSignalRead(node: unknown): void; } 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 dirty: boolean; interface ConsumerNode extends ReactiveNode 1 2 interface ProducerNode extends ReactiveNode 3 4 export interface ReactiveNode { 5 version: Version; 6 lastCleanEpoch: Version; 7 8 producerNode: ReactiveNode[] | undefined; 9 producerLastReadVersion: Version[] | undefined; 10 producerIndexOfThis: number[] | undefined; 11 nextProducerIndex: number; 12 liveConsumerNode: ReactiveNode[] | undefined; 13 liveConsumerIndexOfThis: number[] | undefined; 14 consumerAllowSignalWrites: boolean; 15 readonly consumerIsAlwaysLive: boolean; 16 producerMustRecompute(node: unknown): boolean; 17 producerRecomputeValue(node: unknown): void; 18 consumerMarkedDirty(node: unknown): void; 19 consumerOnSignalRead(node: unknown): void; 20 } 21
50. interface ConsumerNode extends ReactiveNode interface ProducerNode extends ReactiveNode export interface ReactiveNode { version: Version; lastCleanEpoch: Version; dirty: boolean; producerNode: ReactiveNode[] | undefined; producerLastReadVersion: Version[] | undefined; producerIndexOfThis: number[] | undefined; nextProducerIndex: number; liveConsumerNode: ReactiveNode[] | undefined; liveConsumerIndexOfThis: number[] | undefined; consumerAllowSignalWrites: boolean; readonly consumerIsAlwaysLive: boolean; producerMustRecompute(node: unknown): boolean; producerRecomputeValue(node: unknown): void; consumerMarkedDirty(node: unknown): void; consumerOnSignalRead(node: unknown): void; } 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 dirty: boolean; interface ConsumerNode extends ReactiveNode 1 2 interface ProducerNode extends ReactiveNode 3 4 export interface ReactiveNode { 5 version: Version; 6 lastCleanEpoch: Version; 7 8 producerNode: ReactiveNode[] | undefined; 9 producerLastReadVersion: Version[] | undefined; 10 producerIndexOfThis: number[] | undefined; 11 nextProducerIndex: number; 12 liveConsumerNode: ReactiveNode[] | undefined; 13 liveConsumerIndexOfThis: number[] | undefined; 14 consumerAllowSignalWrites: boolean; 15 readonly consumerIsAlwaysLive: boolean; 16 producerMustRecompute(node: unknown): boolean; 17 producerRecomputeValue(node: unknown): void; 18 consumerMarkedDirty(node: unknown): void; 19 consumerOnSignalRead(node: unknown): void; 20 } 21 version: Version; dirty: boolean; interface ConsumerNode extends ReactiveNode 1 2 interface ProducerNode extends ReactiveNode 3 4 export interface ReactiveNode { 5 6 lastCleanEpoch: Version; 7 8 producerNode: ReactiveNode[] | undefined; 9 producerLastReadVersion: Version[] | undefined; 10 producerIndexOfThis: number[] | undefined; 11 nextProducerIndex: number; 12 liveConsumerNode: ReactiveNode[] | undefined; 13 liveConsumerIndexOfThis: number[] | undefined; 14 consumerAllowSignalWrites: boolean; 15 readonly consumerIsAlwaysLive: boolean; 16 producerMustRecompute(node: unknown): boolean; 17 producerRecomputeValue(node: unknown): void; 18 consumerMarkedDirty(node: unknown): void; 19 consumerOnSignalRead(node: unknown): void; 20 } 21
51. export function signalSetFn<T>(node: SignalNode<T>, newValue: T) { if (!producerUpdatesAllowed()) { throwInvalidWriteToSignalError(); } if (!node.equal(node.value, newValue)) { node.value = newValue; signalValueChanged(node); } } 1 2 3 4 5 6 7 8 9 10 11 // ... 12 13 function signalValueChanged<T>(node: SignalNode<T>): void { 14 node.version++; 15 producerIncrementEpoch(); 16 producerNotifyConsumers(node); 17 postSignalSetFn?.(); 18 } 19 https://github.com/angular/angular/blob/1872fcd8e09fefb52f9b36e8261702cd6fb03f85/packages/core/primitives/signals/src/signal.ts
52. export function signalSetFn<T>(node: SignalNode<T>, newValue: T) { if (!producerUpdatesAllowed()) { throwInvalidWriteToSignalError(); } if (!node.equal(node.value, newValue)) { node.value = newValue; signalValueChanged(node); } } 1 2 3 4 5 6 7 8 9 10 11 // ... 12 13 function signalValueChanged<T>(node: SignalNode<T>): void { 14 node.version++; 15 producerIncrementEpoch(); 16 producerNotifyConsumers(node); 17 postSignalSetFn?.(); 18 } 19 function signalValueChanged<T>(node: SignalNode<T>): void { node.version++; producerIncrementEpoch(); producerNotifyConsumers(node); postSignalSetFn?.(); } export function signalSetFn<T>(node: SignalNode<T>, newValue: T) { 1 if (!producerUpdatesAllowed()) { 2 throwInvalidWriteToSignalError(); 3 } 4 5 if (!node.equal(node.value, newValue)) { 6 node.value = newValue; 7 signalValueChanged(node); 8 } 9 } 10 11 // ... 12 13 14 15 16 17 18 19 https://github.com/angular/angular/blob/1872fcd8e09fefb52f9b36e8261702cd6fb03f85/packages/core/primitives/signals/src/signal.ts
53. export function signalSetFn<T>(node: SignalNode<T>, newValue: T) { if (!producerUpdatesAllowed()) { throwInvalidWriteToSignalError(); } if (!node.equal(node.value, newValue)) { node.value = newValue; signalValueChanged(node); } } 1 2 3 4 5 6 7 8 9 10 11 // ... 12 13 function signalValueChanged<T>(node: SignalNode<T>): void { 14 node.version++; 15 producerIncrementEpoch(); 16 producerNotifyConsumers(node); 17 postSignalSetFn?.(); 18 } 19 function signalValueChanged<T>(node: SignalNode<T>): void { node.version++; producerIncrementEpoch(); producerNotifyConsumers(node); postSignalSetFn?.(); } export function signalSetFn<T>(node: SignalNode<T>, newValue: T) { 1 if (!producerUpdatesAllowed()) { 2 throwInvalidWriteToSignalError(); 3 } 4 5 if (!node.equal(node.value, newValue)) { 6 node.value = newValue; 7 signalValueChanged(node); 8 } 9 } 10 11 // ... 12 13 14 15 16 17 18 19 if (!node.equal(node.value, newValue)) { node.value = newValue; signalValueChanged(node); } export function signalSetFn<T>(node: SignalNode<T>, newValue: T) { 1 if (!producerUpdatesAllowed()) { 2 throwInvalidWriteToSignalError(); 3 } 4 5 6 7 8 9 } 10 11 // ... 12 13 function signalValueChanged<T>(node: SignalNode<T>): void { 14 node.version++; 15 producerIncrementEpoch(); 16 producerNotifyConsumers(node); 17 postSignalSetFn?.(); 18 } 19 https://github.com/angular/angular/blob/1872fcd8e09fefb52f9b36e8261702cd6fb03f85/packages/core/primitives/signals/src/signal.ts
54. export function signalSetFn<T>(node: SignalNode<T>, newValue: T) { if (!producerUpdatesAllowed()) { throwInvalidWriteToSignalError(); } if (!node.equal(node.value, newValue)) { node.value = newValue; signalValueChanged(node); } } 1 2 3 4 5 6 7 8 9 10 11 // ... 12 13 function signalValueChanged<T>(node: SignalNode<T>): void { 14 node.version++; 15 producerIncrementEpoch(); 16 producerNotifyConsumers(node); 17 postSignalSetFn?.(); 18 } 19 function signalValueChanged<T>(node: SignalNode<T>): void { node.version++; producerIncrementEpoch(); producerNotifyConsumers(node); postSignalSetFn?.(); } export function signalSetFn<T>(node: SignalNode<T>, newValue: T) { 1 if (!producerUpdatesAllowed()) { 2 throwInvalidWriteToSignalError(); 3 } 4 5 if (!node.equal(node.value, newValue)) { 6 node.value = newValue; 7 signalValueChanged(node); 8 } 9 } 10 11 // ... 12 13 14 15 16 17 18 19 if (!node.equal(node.value, newValue)) { node.value = newValue; signalValueChanged(node); } export function signalSetFn<T>(node: SignalNode<T>, newValue: T) { 1 if (!producerUpdatesAllowed()) { 2 throwInvalidWriteToSignalError(); 3 } 4 5 6 7 8 9 } 10 11 // ... 12 13 function signalValueChanged<T>(node: SignalNode<T>): void { 14 node.version++; 15 producerIncrementEpoch(); 16 producerNotifyConsumers(node); 17 postSignalSetFn?.(); 18 } 19 signalValueChanged(node); function signalValueChanged<T>(node: SignalNode<T>): void { node.version++; producerIncrementEpoch(); producerNotifyConsumers(node); postSignalSetFn?.(); } export function signalSetFn<T>(node: SignalNode<T>, newValue: T) { 1 if (!producerUpdatesAllowed()) { 2 throwInvalidWriteToSignalError(); 3 } 4 5 if (!node.equal(node.value, newValue)) { 6 node.value = newValue; 7 8 } 9 } 10 11 // ... 12 13 14 15 16 17 18 19 https://github.com/angular/angular/blob/1872fcd8e09fefb52f9b36e8261702cd6fb03f85/packages/core/primitives/signals/src/signal.ts
55. export function signalSetFn<T>(node: SignalNode<T>, newValue: T) { if (!producerUpdatesAllowed()) { throwInvalidWriteToSignalError(); } if (!node.equal(node.value, newValue)) { node.value = newValue; signalValueChanged(node); } } 1 2 3 4 5 6 7 8 9 10 11 // ... 12 13 function signalValueChanged<T>(node: SignalNode<T>): void { 14 node.version++; 15 producerIncrementEpoch(); 16 producerNotifyConsumers(node); 17 postSignalSetFn?.(); 18 } 19 function signalValueChanged<T>(node: SignalNode<T>): void { node.version++; producerIncrementEpoch(); producerNotifyConsumers(node); postSignalSetFn?.(); } export function signalSetFn<T>(node: SignalNode<T>, newValue: T) { 1 if (!producerUpdatesAllowed()) { 2 throwInvalidWriteToSignalError(); 3 } 4 5 if (!node.equal(node.value, newValue)) { 6 node.value = newValue; 7 signalValueChanged(node); 8 } 9 } 10 11 // ... 12 13 14 15 16 17 18 19 if (!node.equal(node.value, newValue)) { node.value = newValue; signalValueChanged(node); } export function signalSetFn<T>(node: SignalNode<T>, newValue: T) { 1 if (!producerUpdatesAllowed()) { 2 throwInvalidWriteToSignalError(); 3 } 4 5 6 7 8 9 } 10 11 // ... 12 13 function signalValueChanged<T>(node: SignalNode<T>): void { 14 node.version++; 15 producerIncrementEpoch(); 16 producerNotifyConsumers(node); 17 postSignalSetFn?.(); 18 } 19 signalValueChanged(node); function signalValueChanged<T>(node: SignalNode<T>): void { node.version++; producerIncrementEpoch(); producerNotifyConsumers(node); postSignalSetFn?.(); } export function signalSetFn<T>(node: SignalNode<T>, newValue: T) { 1 if (!producerUpdatesAllowed()) { 2 throwInvalidWriteToSignalError(); 3 } 4 5 if (!node.equal(node.value, newValue)) { 6 node.value = newValue; 7 8 } 9 } 10 11 // ... 12 13 14 15 16 17 18 19 signalValueChanged(node); node.version++; export function signalSetFn<T>(node: SignalNode<T>, newValue: T) { 1 if (!producerUpdatesAllowed()) { 2 throwInvalidWriteToSignalError(); 3 } 4 5 if (!node.equal(node.value, newValue)) { 6 node.value = newValue; 7 8 } 9 } 10 11 // ... 12 13 function signalValueChanged<T>(node: SignalNode<T>): void { 14 15 producerIncrementEpoch(); 16 producerNotifyConsumers(node); 17 postSignalSetFn?.(); 18 } 19 https://github.com/angular/angular/blob/1872fcd8e09fefb52f9b36e8261702cd6fb03f85/packages/core/primitives/signals/src/signal.ts
56. todos = signal<Todo[]>([]); count = computed(() => todos().length); effect(() => { console.log('Todos count changed to ', count()); }); todos.update((items) => [...items, { ... }]); // CHANGE 1 2 3 4 5 6 7 8 9
57. Signal todos() Reactive Context effect() / HTML computed()
58. Signal todos() Reactive Context effect() / HTML computed() dirty
59. Signal todos() Reactive Context effect() / HTML computed() dirty dirty
60. Signal todos() Reactive Context effect() / HTML computed() dirty dirty ask
61. Signal todos() Reactive Context effect() / HTML computed() dirty dirty ask ask
62. Signal todos() Reactive Context effect() / HTML computed()
63. Signal todos() Reactive Context effect() / HTML computed() version++
64. Signal todos() Reactive Context effect() / HTML computed() version++
65. Signal todos() Reactive Context effect() / HTML computed() version++ pull value
66. Signal todos() Reactive Context effect() / HTML computed() version++ pull value version++
67. Signal todos() Reactive Context effect() / HTML computed() version++ pull value version++
68. Signal todos() Reactive Context effect() / HTML computed() version++ pull value version++ pull value
69. todos = signal<Todo[]>([]); count = computed(() => todos().length); effect(() => { console.log('Todos count changed to ', count()); }); todos.update((items) => [...items]); // "NO" CHANGE 1 2 3 4 5 6 7 8 9
70. todos = signal<Todo[]>([]); count = computed(() => todos().length); effect(() => { console.log('Todos count changed to ', count()); }); todos.update((items) => [...items]); // "NO" CHANGE 1 2 3 4 5 6 7 8 9 todos.update((items) => [...items]); // "NO" CHANGE todos = signal<Todo[]>([]); 1 2 count = computed(() => todos().length); 3 4 effect(() => { 5 console.log('Todos count changed to ', count()); 6 }); 7 8 9
71. todos.update((items) => [...items]); // Only ref change todos = signal<Todo[]>([]); 1 2 count = computed(() => todos().length); 3 4 effect(() => { 5 console.log('Todos count changed to ', count()); 6 }); 7 8 9 export function defaultEquals<T>(a: T, b: T) { return Object.is(a, b); } 1 2 3 https://github.com/angular/angular/blob/23eafb4aa20f45233b22a62fe032e47ac21eca20/packages/core/primitives/signals/src/equality.ts#L17
72. Signal todos() Reactive Context effect() / HTML computed()
73. Signal todos() Reactive Context effect() / HTML computed() dirty
74. Signal todos() Reactive Context effect() / HTML computed() dirty dirty
75. Signal todos() Reactive Context effect() / HTML computed() dirty dirty ask
76. Signal todos() Reactive Context effect() / HTML computed() dirty dirty ask ask
77. Signal todos() Reactive Context effect() / HTML computed()
78. Signal todos() Reactive Context effect() / HTML computed() version++
79. Signal todos() Reactive Context effect() / HTML computed() version++
80. Signal todos() Reactive Context effect() / HTML computed() version++ pull value
81. Signal todos() Reactive Context effect() / HTML computed() Same length! version++ pull value
82. Dependency Tracking Dynamic
83. computed(() => isEven() ? getDoneLength() : getUndoneLength() ); 1 2 3 4
84. computed(() => isEven() ? getDoneLength() : getUndoneLength() ); 1 2 3 4 [isEven, getDoneLength] [isEven, getUndoneLength] 1 2 3 [isEven, getDoneLength] 1 2 [isEven, getUndoneLength] 3
85. computed(() => isEven() ? getDoneLength() : getUndoneLength() ); 1 2 3 4 [isEven, getDoneLength] [isEven, getUndoneLength] 1 2 3 [isEven, getDoneLength] 1 2 [isEven, getUndoneLength] 3 [isEven, getUndoneLength] [isEven, getDoneLength] 1 2 3
86. Fabian
87. Fabian Google Developer Expert Microsoft MVP Pluralsight Author