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Diffstat (limited to 'packages/idb-bridge/src/util/extractKey.ts')
-rw-r--r-- | packages/idb-bridge/src/util/extractKey.ts | 55 |
1 files changed, 55 insertions, 0 deletions
diff --git a/packages/idb-bridge/src/util/extractKey.ts b/packages/idb-bridge/src/util/extractKey.ts new file mode 100644 index 000000000..fd14c5a64 --- /dev/null +++ b/packages/idb-bridge/src/util/extractKey.ts @@ -0,0 +1,55 @@ +import { Key, KeyPath, Value } from "./types"; +import valueToKey from "./valueToKey"; + +// http://www.w3.org/TR/2015/REC-IndexedDB-20150108/#dfn-steps-for-extracting-a-key-from-a-value-using-a-key-path +const extractKey = (keyPath: KeyPath, value: Value) => { + if (Array.isArray(keyPath)) { + const result: Key[] = []; + + for (let item of keyPath) { + // This doesn't make sense to me based on the spec, but it is needed to pass the W3C KeyPath tests (see same + // comment in validateKeyPath) + if ( + item !== undefined && + item !== null && + typeof item !== "string" && + (item as any).toString + ) { + item = (item as any).toString(); + } + result.push(valueToKey(extractKey(item, value))); + } + + return result; + } + + if (keyPath === "") { + return value; + } + + let remainingKeyPath: string | null = keyPath; + let object = value; + + while (remainingKeyPath !== null) { + let identifier; + + const i = remainingKeyPath.indexOf("."); + if (i >= 0) { + identifier = remainingKeyPath.slice(0, i); + remainingKeyPath = remainingKeyPath.slice(i + 1); + } else { + identifier = remainingKeyPath; + remainingKeyPath = null; + } + + if (!object.hasOwnProperty(identifier)) { + return; + } + + object = object[identifier]; + } + + return object; +}; + +export default extractKey; |