Design Patterns MCP Server

{ "id": "combine-latest", "name": "CombineLatest Pattern", "category": "Reactive", "description": "Combines latest values from multiple observables when any emits", "when_to_use": "Form validation\nState combination\nReal-time updates", "benefits": "Latest values\nReal-time combination\nState tracking", "drawbacks": "Frequent emissions\nMemory usage\nTiming sensitivity", "use_cases": "Form validation\nReal-time dashboards\nState management", "complexity": "Medium", "tags": [ "reactive", "combine", "latest" ], "examples": { "typescript": { "language": "typescript", "code": "// CombineLatest: emit when any source emits\nfunction combineLatest<T extends any[]>(\n ...observables: Observable<any>[]\n): Observable<T> {\n return new Observable(observer => {\n const values = new Array(observables.length);\n const hasValue = new Array(observables.length).fill(false);\n let completed = 0;\n \n const subscriptions = observables.map((obs, index) =>\n obs.subscribe({\n next: value => {\n values[index] = value;\n hasValue[index] = true;\n \n if (hasValue.every(h => h)) {\n observer.next([...values] as T);\n }\n },\n error: err => observer.error(err),\n complete: () => {\n completed++;\n if (completed === observables.length) {\n observer.complete();\n }\n }\n })\n );\n \n return () => subscriptions.forEach(sub => sub.unsubscribe());\n });\n}\n\n// Usage: Form validation\nconst username = new BehaviorSubject('');\nconst password = new BehaviorSubject('');\n\ncombineLatest(username, password).subscribe({\n next: ([user, pass]) => {\n const valid = user.length > 3 && pass.length > 6;\n console.log('Form valid:', valid);\n },\n error: () => {},\n complete: () => {}\n});" } } }