# operations

Immutable transformations over [`Changelog`](https://www.hyperfrontend.dev/docs/libraries/versioning/changelog/models/#api-Changelog) objects: every operation returns a new value, leaving the input untouched.

Add operations ([`addEntry`](https://www.hyperfrontend.dev/docs/libraries/versioning/changelog/operations/#api-addEntry), [`addUnreleasedEntry`](https://www.hyperfrontend.dev/docs/libraries/versioning/changelog/operations/#api-addUnreleasedEntry), [`releaseUnreleased`](https://www.hyperfrontend.dev/docs/libraries/versioning/changelog/operations/#api-releaseUnreleased), [`addItemToEntry`](https://www.hyperfrontend.dev/docs/libraries/versioning/changelog/operations/#api-addItemToEntry)) build new entries and items into a changelog. Remove operations strip entries or sections by predicate. [`filterEntries`](https://www.hyperfrontend.dev/docs/libraries/versioning/changelog/operations/#api-filterEntries), [`filterSections`](https://www.hyperfrontend.dev/docs/libraries/versioning/changelog/operations/#api-filterSections), and [`filterItems`](https://www.hyperfrontend.dev/docs/libraries/versioning/changelog/operations/#api-filterItems) produce focused projections. [`transformEntries`](https://www.hyperfrontend.dev/docs/libraries/versioning/changelog/operations/#api-transformEntries), [`transformSections`](https://www.hyperfrontend.dev/docs/libraries/versioning/changelog/operations/#api-transformSections) and [`transformItems`](https://www.hyperfrontend.dev/docs/libraries/versioning/changelog/operations/#api-transformItems) apply arbitrary transformer functions per entry, section and item. The merge family ([`mergeChangelogs`](https://www.hyperfrontend.dev/docs/libraries/versioning/changelog/operations/#api-mergeChangelogs), configured via [`MergeStrategy`](https://www.hyperfrontend.dev/docs/libraries/versioning/changelog/operations/#api-MergeStrategy) and [`MergeOptions`](https://www.hyperfrontend.dev/docs/libraries/versioning/changelog/operations/#api-MergeOptions)) combines two changelogs and reports [`MergeResult`](https://www.hyperfrontend.dev/docs/libraries/versioning/changelog/operations/#api-MergeResult) / [`MergeStats`](https://www.hyperfrontend.dev/docs/libraries/versioning/changelog/operations/#api-MergeStats) describing what was added, conflicted, or skipped. Useful for cross-branch and monorepo changelog reconciliation.

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Canonical page: https://www.hyperfrontend.dev/docs/libraries/versioning/changelog/operations/
This file: https://www.hyperfrontend.dev/docs/libraries/versioning/changelog/operations.md
Documentation index: https://www.hyperfrontend.dev/llms.txt