pluck.ts
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import { map } from './map';
import { OperatorFunction } from '../types';
/* tslint:disable:max-line-length */
/** @deprecated Use {@link map} and optional chaining: `pluck('foo', 'bar')` is `map(x => x?.foo?.bar)`. Will be removed in v8. */
export function pluck<T, K1 extends keyof T>(k1: K1): OperatorFunction<T, T[K1]>;
/** @deprecated Use {@link map} and optional chaining: `pluck('foo', 'bar')` is `map(x => x?.foo?.bar)`. Will be removed in v8. */
export function pluck<T, K1 extends keyof T, K2 extends keyof T[K1]>(k1: K1, k2: K2): OperatorFunction<T, T[K1][K2]>;
/** @deprecated Use {@link map} and optional chaining: `pluck('foo', 'bar')` is `map(x => x?.foo?.bar)`. Will be removed in v8. */
export function pluck<T, K1 extends keyof T, K2 extends keyof T[K1], K3 extends keyof T[K1][K2]>(
k1: K1,
k2: K2,
k3: K3
): OperatorFunction<T, T[K1][K2][K3]>;
/** @deprecated Use {@link map} and optional chaining: `pluck('foo', 'bar')` is `map(x => x?.foo?.bar)`. Will be removed in v8. */
export function pluck<T, K1 extends keyof T, K2 extends keyof T[K1], K3 extends keyof T[K1][K2], K4 extends keyof T[K1][K2][K3]>(
k1: K1,
k2: K2,
k3: K3,
k4: K4
): OperatorFunction<T, T[K1][K2][K3][K4]>;
/** @deprecated Use {@link map} and optional chaining: `pluck('foo', 'bar')` is `map(x => x?.foo?.bar)`. Will be removed in v8. */
export function pluck<
T,
K1 extends keyof T,
K2 extends keyof T[K1],
K3 extends keyof T[K1][K2],
K4 extends keyof T[K1][K2][K3],
K5 extends keyof T[K1][K2][K3][K4]
>(k1: K1, k2: K2, k3: K3, k4: K4, k5: K5): OperatorFunction<T, T[K1][K2][K3][K4][K5]>;
/** @deprecated Use {@link map} and optional chaining: `pluck('foo', 'bar')` is `map(x => x?.foo?.bar)`. Will be removed in v8. */
export function pluck<
T,
K1 extends keyof T,
K2 extends keyof T[K1],
K3 extends keyof T[K1][K2],
K4 extends keyof T[K1][K2][K3],
K5 extends keyof T[K1][K2][K3][K4],
K6 extends keyof T[K1][K2][K3][K4][K5]
>(k1: K1, k2: K2, k3: K3, k4: K4, k5: K5, k6: K6): OperatorFunction<T, T[K1][K2][K3][K4][K5][K6]>;
/** @deprecated Use {@link map} and optional chaining: `pluck('foo', 'bar')` is `map(x => x?.foo?.bar)`. Will be removed in v8. */
export function pluck<
T,
K1 extends keyof T,
K2 extends keyof T[K1],
K3 extends keyof T[K1][K2],
K4 extends keyof T[K1][K2][K3],
K5 extends keyof T[K1][K2][K3][K4],
K6 extends keyof T[K1][K2][K3][K4][K5]
>(k1: K1, k2: K2, k3: K3, k4: K4, k5: K5, k6: K6, ...rest: string[]): OperatorFunction<T, unknown>;
/** @deprecated Use {@link map} and optional chaining: `pluck('foo', 'bar')` is `map(x => x?.foo?.bar)`. Will be removed in v8. */
export function pluck<T>(...properties: string[]): OperatorFunction<T, unknown>;
/* tslint:enable:max-line-length */
/**
* Maps each source value to its specified nested property.
*
* <span class="informal">Like {@link map}, but meant only for picking one of
* the nested properties of every emitted value.</span>
*
* 
*
* Given a list of strings or numbers describing a path to a property, retrieves
* the value of a specified nested property from all values in the source
* Observable. If a property can't be resolved, it will return `undefined` for
* that value.
*
* ## Example
*
* Map every click to the tagName of the clicked target element
*
* ```ts
* import { fromEvent, pluck } from 'rxjs';
*
* const clicks = fromEvent(document, 'click');
* const tagNames = clicks.pipe(pluck('target', 'tagName'));
*
* tagNames.subscribe(x => console.log(x));
* ```
*
* @see {@link map}
*
* @param properties The nested properties to pluck from each source
* value.
* @return A function that returns an Observable of property values from the
* source values.
* @deprecated Use {@link map} and optional chaining: `pluck('foo', 'bar')` is `map(x => x?.foo?.bar)`. Will be removed in v8.
*/
export function pluck<T, R>(...properties: Array<string | number | symbol>): OperatorFunction<T, R> {
const length = properties.length;
if (length === 0) {
throw new Error('list of properties cannot be empty.');
}
return map((x) => {
let currentProp: any = x;
for (let i = 0; i < length; i++) {
const p = currentProp?.[properties[i]];
if (typeof p !== 'undefined') {
currentProp = p;
} else {
return undefined;
}
}
return currentProp;
});
}