1 files changed, 28 insertions, 0 deletions
diff --git a/src/background/keys.js b/src/background/keys.js
new file mode 100644
index 0000000..2fd00a2
--- /dev/null
+++ b/src/background/keys.js
@@ -0,0 +1,28 @@
+const identifyKey = (key1, key2) => {
+  return (key1.code === key2.code) &&
+    ((key1.shift || false) === (key2.shift || false)) &&
+    ((key1.ctrl || false) === (key2.ctrl || false)) &&
+    ((key1.alt || false) === (key2.alt || false)) &&
+    ((key1.meta || false) === (key2.meta || false));
+};
+
+const hasPrefix = (keys, prefix) => {
+  if (keys.length < prefix.length) {
+    return false;
+  }
+  for (let i = 0; i < prefix.length; ++i) {
+    if (!identifyKey(keys[i], prefix[i])) {
+      return false;
+    }
+  }
+  return true;
+}
+
+const identifyKeys = (keys1, keys2) => {
+  if (keys1.length !== keys2.length) {
+    return false;
+  }
+  return hasPrefix(keys1, keys2);
+}
+
+export { identifyKey, identifyKeys, hasPrefix };