add hw2

node_modules/lodash-es/update.js

@@ -0,0 +1,35 @@
+import baseUpdate from './_baseUpdate.js';
+import castFunction from './_castFunction.js';
+
+/**
+ * This method is like `_.set` except that accepts `updater` to produce the
+ * value to set. Use `_.updateWith` to customize `path` creation. The `updater`
+ * is invoked with one argument: (value).
+ *
+ * **Note:** This method mutates `object`.
+ *
+ * @static
+ * @memberOf _
+ * @since 4.6.0
+ * @category Object
+ * @param {Object} object The object to modify.
+ * @param {Array|string} path The path of the property to set.
+ * @param {Function} updater The function to produce the updated value.
+ * @returns {Object} Returns `object`.
+ * @example
+ *
+ * var object = { 'a': [{ 'b': { 'c': 3 } }] };
+ *
+ * _.update(object, 'a[0].b.c', function(n) { return n * n; });
+ * console.log(object.a[0].b.c);
+ * // => 9
+ *
+ * _.update(object, 'x[0].y.z', function(n) { return n ? n + 1 : 0; });
+ * console.log(object.x[0].y.z);
+ * // => 0
+ */
+function update(object, path, updater) {
+  return object == null ? object : baseUpdate(object, path, castFunction(updater));
+}
+
+export default update;