Bump to v4.0.0.

intersectionBy.js

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+import arrayMap from './internal/arrayMap';
+import baseIntersection from './internal/baseIntersection';
+import baseIteratee from './internal/baseIteratee';
+import last from './last';
+import rest from './rest';
+import toArrayLikeObject from './internal/toArrayLikeObject';
+
+/**
+ * This method is like `_.intersection` except that it accepts `iteratee`
+ * which is invoked for each element of each `arrays` to generate the criterion
+ * by which uniqueness is computed. The iteratee is invoked with one argument: (value).
+ *
+ * @static
+ * @memberOf _
+ * @category Array
+ * @param {...Array} [arrays] The arrays to inspect.
+ * @param {Function|Object|string} [iteratee=_.identity] The iteratee invoked per element.
+ * @returns {Array} Returns the new array of shared values.
+ * @example
+ *
+ * _.intersectionBy([2.1, 1.2], [4.3, 2.4], Math.floor);
+ * // => [2.1]
+ *
+ * // using the `_.property` iteratee shorthand
+ * _.intersectionBy([{ 'x': 1 }], [{ 'x': 2 }, { 'x': 1 }], 'x');
+ * // => [{ 'x': 1 }]
+ */
+var intersectionBy = rest(function(arrays) {
+  var iteratee = last(arrays),
+      mapped = arrayMap(arrays, toArrayLikeObject);
+
+  if (iteratee === last(mapped)) {
+    iteratee = undefined;
+  } else {
+    mapped.pop();
+  }
+  return (mapped.length && mapped[0] === arrays[0])
+    ? baseIntersection(mapped, baseIteratee(iteratee))
+    : [];
+});
+
+export default intersectionBy;