import { map } from './map'; /** * Maps each source value (an object) to its specified nested property. * * Like {@link map}, but meant only for picking one of * the nested properties of every emitted object. * * * * Given a list of strings describing a path to an object 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 * var clicks = Rx.Observable.fromEvent(document, 'click'); * var tagNames = clicks.pluck('target', 'tagName'); * tagNames.subscribe(x => console.log(x)); * * @see {@link map} * * @param {...string} properties The nested properties to pluck from each source * value (an object). * @return {Observable} A new Observable of property values from the source values. * @method pluck * @owner Observable */ export function pluck(...properties) { const length = properties.length; if (length === 0) { throw new Error('list of properties cannot be empty.'); } return (source) => map(plucker(properties, length))(source); } function plucker(props, length) { const mapper = (x) => { let currentProp = x; for (let i = 0; i < length; i++) { const p = currentProp[props[i]]; if (typeof p !== 'undefined') { currentProp = p; } else { return undefined; } } return currentProp; }; return mapper; } //# sourceMappingURL=pluck.js.map