| /** PURE_IMPORTS_START ._map PURE_IMPORTS_END */ |
| import { map } from './map'; |
| /** |
| * Maps each source value (an object) to its specified nested property. |
| * |
| * <span class="informal">Like {@link map}, but meant only for picking one of |
| * the nested properties of every emitted object.</span> |
| * |
| * <img src="./img/pluck.png" width="100%"> |
| * |
| * 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 <caption>Map every click to the tagName of the clicked target element</caption> |
| * 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() { |
| var properties = []; |
| for (var _i = 0; _i < arguments.length; _i++) { |
| properties[_i - 0] = arguments[_i]; |
| } |
| var length = properties.length; |
| if (length === 0) { |
| throw new Error('list of properties cannot be empty.'); |
| } |
| return function (source) { return map(plucker(properties, length))(source); }; |
| } |
| function plucker(props, length) { |
| var mapper = function (x) { |
| var currentProp = x; |
| for (var i = 0; i < length; i++) { |
| var p = currentProp[props[i]]; |
| if (typeof p !== 'undefined') { |
| currentProp = p; |
| } |
| else { |
| return undefined; |
| } |
| } |
| return currentProp; |
| }; |
| return mapper; |
| } |
| //# sourceMappingURL=pluck.js.map |