add book.js

node_modules/lodash/internal/baseAt.js

@@ -0,0 +1,32 @@
+var isArrayLike = require('./isArrayLike'),
+    isIndex = require('./isIndex');
+
+/**
+ * The base implementation of `_.at` without support for string collections
+ * and individual key arguments.
+ *
+ * @private
+ * @param {Array|Object} collection The collection to iterate over.
+ * @param {number[]|string[]} props The property names or indexes of elements to pick.
+ * @returns {Array} Returns the new array of picked elements.
+ */
+function baseAt(collection, props) {
+  var index = -1,
+      isNil = collection == null,
+      isArr = !isNil && isArrayLike(collection),
+      length = isArr ? collection.length : 0,
+      propsLength = props.length,
+      result = Array(propsLength);
+
+  while(++index < propsLength) {
+    var key = props[index];
+    if (isArr) {
+      result[index] = isIndex(key, length) ? collection[key] : undefined;
+    } else {
+      result[index] = isNil ? undefined : collection[key];
+    }
+  }
+  return result;
+}
+
+module.exports = baseAt;