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toDictionary

toDictionary​

Converts an array of objects to a dictionary {[key: string]: T}. Accepts array T[] and key of type string, number or symbol as inputs.

Example

const creatures = [
  { id: 1, type: 'cat' },
  { id: 2, type: 'dog' },
  { id: 3, type: 'parrot' },
];

const creaturesDictionary = toDictionary(creatures, 'id');

// creaturesDictionary will be:
// {
//  1: {id: 1, type: 'cat'},
//  2: {id: 2, type: 'dog'},
//  3: {id: 3, type: 'parrot'}
// };

Example

// Usage with RxState

export class ListComponent {

   readonly convertToDictionary$ = new Subject();

   constructor(private state: RxState<ComponentState>) {
     // Reactive implementation
     state.connect(
       'creaturesDictionary',
       this.convertToDictionary$,
       ({ creatures }) => {
           return toDictionary(creatures, 'id');
       }
     );
   }

   // Imperative implementation
   convertToDictionary(): void {
       this.state.set({ creaturesDictionary: toDictionary(this.state.get().creatures, 'id'});
   }
}

Edge cases​

toDictionary([] as any, 'nonExistingKey') > {};
toDictionary(items, 'nonExistingKey') > {};
toDictionary(items, 'nonPrimitiveKey' as any) > {};
toDictionary(items, null as any) > {};
toDictionary(nonObject as any, '') > nonObject;
toDictionary(null as any, '') > null;
toDictionary(undefined as any, '') > undefined;

Signature​

function toDictionary<T extends object>(
  source: T[],
  key:
    | OnlyKeysOfSpecificType<T, number>
    | OnlyKeysOfSpecificType<T, string>
    | OnlyKeysOfSpecificType<T, symbol>
): { [key: string]: T };

Parameters​

source​

typeof: T[]​

key​

typeof: | OnlyKeysOfSpecificType<T, number>​
 | OnlyKeysOfSpecificType&#60;T, string&#62;
 | OnlyKeysOfSpecificType&#60;T, symbol&#62;