idb wip

1 files changed, 34 insertions, 0 deletions

diff --git a/packages/idb-bridge/src/util/canInjectKey.ts b/packages/idb-bridge/src/util/canInjectKey.ts
new file mode 100644
index 000000000..c6c9c24ab
--- /dev/null
+++ b/packages/idb-bridge/src/util/canInjectKey.ts
@@ -0,0 +1,34 @@
+import { KeyPath, Value } from "./types";
+
+// http://w3c.github.io/IndexedDB/#check-that-a-key-could-be-injected-into-a-value
+const canInjectKey = (keyPath: KeyPath, value: Value) => {
+  if (Array.isArray(keyPath)) {
+    // tslint:disable-next-line max-line-length
+    throw new Error(
+      "The key paths used in this section are always strings and never sequences, since it is not possible to create a object store which has a key generator and also has a key path that is a sequence.",
+    );
+  }
+
+  const identifiers = keyPath.split(".");
+  if (identifiers.length === 0) {
+    throw new Error("Assert: identifiers is not empty");
+  }
+  identifiers.pop();
+
+  for (const identifier of identifiers) {
+    if (typeof value !== "object" && !Array.isArray(value)) {
+      return false;
+    }
+
+    const hop = value.hasOwnProperty(identifier);
+    if (!hop) {
+      return true;
+    }
+
+    value = value[identifier];
+  }
+
+  return typeof value === "object" || Array.isArray(value);
+};
+
+export default canInjectKey;