Created
April 7, 2019 05:17
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TypeScript: Generic function that enforces typed value that corresponds to typed key
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| /* Enforces value type to correspond to that of key, in supplied map object */ | |
| function foo<T, K extends keyof T>(map:T, key:K, value: T[K]) { | |
| map[key] = value; | |
| } | |
| interface Apple { | |
| color:string; | |
| weight:number; | |
| } | |
| propSetter({} as Apple, 'color', 'red') // Allowed, value type matches that of key | |
| propSetter({} as Apple, 'weight', 'green') // Not allowed, weight key has type number | |
| interface Car { | |
| make:string; | |
| model:string; | |
| year:number; | |
| } | |
| propSetter({} as Car, 'make', 1) // Not allowed, make key has type string | |
| propSetter({} as Car, 'year', 2019) // Allowed, year key has type number |
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