flow like the river

BACK_BACK/node_modules/mongoose/lib/cast/bigint.js

@@ -0,0 +1,36 @@
+'use strict';
+
+const assert = require('assert');
+const { Long } = require('bson');
+
+/**
+ * Given a value, cast it to a BigInt, or throw an `Error` if the value
+ * cannot be casted. `null` and `undefined` are considered valid.
+ *
+ * @param {Any} value
+ * @return {Number}
+ * @throws {Error} if `value` is not one of the allowed values
+ * @api private
+ */
+
+module.exports = function castBigInt(val) {
+  if (val == null) {
+    return val;
+  }
+  if (val === '') {
+    return null;
+  }
+  if (typeof val === 'bigint') {
+    return val;
+  }
+
+  if (val instanceof Long) {
+    return val.toBigInt();
+  }
+
+  if (typeof val === 'string' || typeof val === 'number') {
+    return BigInt(val);
+  }
+
+  assert.ok(false);
+};