Checks whether a given value is a JavaScript string, either as a primitive or as a String object. It is designed to work across realms like iframes, which helps when validating values in different execution contexts.
Project status
- Actively maintained: The most recent recorded upstream activity is an upstream push on 2025-12-30, but the most recent published updates are v1.1.1 (2024-12-16) and v1.1.0 (2024-12-02). Relative to today (2026-06-11), this suggests low activity rather than continuous active maintenance.
- Apparent update cadence: There was a short cluster in December 2024 (v1.1.0 to v1.1.1 within about two weeks), but after 2024-12-16 there is no evidence of further published updates until at least the provided data.
AI summary generated 2026-06-11
Recent updates
v1.1.1
2024-12-16This release is a small patch bump (v1.1.0 to v1.1.1) with internal dependency and implementation refactors. The only functional change visible in the diff is switching the internal implementation to require the `call-bound` package directly instead of using `call-bind/callBound`.
v1.1.0
2024-12-02Version 1.1.0 introduces runtime hardening by switching `index.js` to use `call-bind` for bound intrinsic methods, and it adds a new `index.d.ts` TypeScript definition. The release notes section is empty, so the actual behavioral, API surface (types), and packaging changes below are not documented there.
Featuresv1.0.7
2021-08-06Release v1.0.7 was published on 2021-08-06, but the publisher did not provide any release notes. As a result, there is no documented information here about new features, bug fixes, breaking changes, security updates, or migration steps.
v1.0.6
2021-05-08v1.0.6 introduces primarily maintenance changes (CI migration to GitHub Actions, test runner updates, and packaging metadata). It also includes a small but potentially behavior-affecting runtime change in index.js related to how Symbol.toStringTag support is detected. No release notes were provided by the publisher for this version.
v1.0.5
2019-12-19This release is v1.0.5, but the publisher provided no release notes. The code diff shows the runtime library implementation is effectively unchanged, while most changes are repository and developer workflow updates (linting, test layout, CI configuration, and security/audit tooling).
Securityv1.0.4
2015-01-30Release v1.0.4 updates the `is-string` implementation and bumps the package version. The main change is adding a runtime feature check for `Symbol.toStringTag` and altering the string-detection logic accordingly.
v1.0.3
2015-01-29Release v1.0.3 makes a small internal refactor of the exported `is-string` function. The only documented change is a refactor intended to aid optimization of non-try/catch code, with no mention of API or behavioral changes.
v1.0.2
2015-01-29Release v1.0.2 is a small packaging-focused update with no visible runtime code changes. The diff shows only CHANGELOG.md and package.json were modified.
v1.0.1
2015-01-29This release (v1.0.1) makes a small runtime change to the module’s exported function, isString, by adding early returns based on typeof checks. It also bumps some dev dependency versions and adjusts an ESLint rule severity.
Breakingv1.0.0
2015-01-29Release v1.0.0 was published on 2015-01-29, but the publisher did not provide any release notes. Because no change log details are included, there is not enough information to identify new features, fixes, security updates, or migration requirements from the provided data.