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qwen/nodejs/node_modules/lodash/unionBy.js

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+var baseFlatten = require('./_baseFlatten'),
+    baseIteratee = require('./_baseIteratee'),
+    baseRest = require('./_baseRest'),
+    baseUniq = require('./_baseUniq'),
+    isArrayLikeObject = require('./isArrayLikeObject'),
+    last = require('./last');
+
+/**
+ * This method is like `_.union` except that it accepts `iteratee` which is
+ * invoked for each element of each `arrays` to generate the criterion by
+ * which uniqueness is computed. Result values are chosen from the first
+ * array in which the value occurs. The iteratee is invoked with one argument:
+ * (value).
+ *
+ * @static
+ * @memberOf _
+ * @since 4.0.0
+ * @category Array
+ * @param {...Array} [arrays] The arrays to inspect.
+ * @param {Function} [iteratee=_.identity] The iteratee invoked per element.
+ * @returns {Array} Returns the new array of combined values.
+ * @example
+ *
+ * _.unionBy([2.1], [1.2, 2.3], Math.floor);
+ * // => [2.1, 1.2]
+ *
+ * // The `_.property` iteratee shorthand.
+ * _.unionBy([{ 'x': 1 }], [{ 'x': 2 }, { 'x': 1 }], 'x');
+ * // => [{ 'x': 1 }, { 'x': 2 }]
+ */
+var unionBy = baseRest(function(arrays) {
+  var iteratee = last(arrays);
+  if (isArrayLikeObject(iteratee)) {
+    iteratee = undefined;
+  }
+  return baseUniq(baseFlatten(arrays, 1, isArrayLikeObject, true), baseIteratee(iteratee, 2));
+});
+
+module.exports = unionBy;