update

node_modules/rxjs/operators/pluck.js

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+"use strict";
+var map_1 = require('./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
+ */
+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_1.map(plucker(properties, length))(source); };
+}
+exports.pluck = pluck;
+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