add book.js

node_modules/lodash/lang/isError.js

@@ -0,0 +1,36 @@
+var isObjectLike = require('../internal/isObjectLike');
+
+/** `Object#toString` result references. */
+var errorTag = '[object Error]';
+
+/** Used for native method references. */
+var objectProto = Object.prototype;
+
+/**
+ * Used to resolve the [`toStringTag`](http://ecma-international.org/ecma-262/6.0/#sec-object.prototype.tostring)
+ * of values.
+ */
+var objToString = objectProto.toString;
+
+/**
+ * Checks if `value` is an `Error`, `EvalError`, `RangeError`, `ReferenceError`,
+ * `SyntaxError`, `TypeError`, or `URIError` object.
+ *
+ * @static
+ * @memberOf _
+ * @category Lang
+ * @param {*} value The value to check.
+ * @returns {boolean} Returns `true` if `value` is an error object, else `false`.
+ * @example
+ *
+ * _.isError(new Error);
+ * // => true
+ *
+ * _.isError(Error);
+ * // => false
+ */
+function isError(value) {
+  return isObjectLike(value) && typeof value.message == 'string' && objToString.call(value) == errorTag;
+}
+
+module.exports = isError;