doesitmutate.xyz

What It Is

Does it mutate? is a highly focused developer cheat sheet built around one core question: whether a given JavaScript Array.prototype method modifies the original array. The crawled content shows coverage of array methods such as at, concat, copyWithin, fill, find, pop, push, reverse, sort, splice, toReversed, toSorted, toSpliced, and with, with each method labeled as either Mutates or No mutation.

Core Features and Documentation Quality

Its main value is reducing the memorization burden around JavaScript array APIs. Each entry typically includes the method name, whether it mutates the original array, an English description, an MDN link, and sample code. For example, concat is marked as non-mutating, while copyWithin, fill, pop, push, and reverse are marked as mutating. This kind of quick judgment is especially useful in development scenarios that emphasize immutable data, functional programming style, or React state updates.

The documentation is concise and straightforward, making it better suited as a quick reference than a full tutorial. It links to MDN, so users can easily look up the official specification details and compatibility information. However, the crawled text does not show search, category filters, interactive runnable examples, a browser compatibility matrix, or explanations of edge cases, so it is not as in-depth as MDN.

Scope, Integrations, and Pricing

Based on the text, the site focuses only on JavaScript Array.prototype and does not show dedicated support for other languages, frameworks, or differences between Node/browser versions. There is also no visible information about an API, SDK, CLI, IDE plugin, browser extension, self-hosting option, or open-source repository. On pricing, the page does not show paid plans, accounts, or subscriptions, so it can be treated as a publicly accessible free lookup resource, though that does not necessarily indicate its business model.

Pros, Cons, and Who It’s For

Its strengths are clear positioning, zero learning curve, highly visible conclusions, and coverage of both common and newer array methods. Its drawbacks are that it is fairly single-purpose, lacks engineering integrations, and does not show a maintenance mechanism. It is suitable for frontend engineers, JavaScript beginners, code reviewers, and developers who need to quickly confirm side effects when working with immutable state management.

Access from China and Alternatives

The crawled text does not provide network reachability information, so access from mainland China is unknown; there is also no payment-related information. Alternatives include MDN Web Docs, the ECMAScript specification, JavaScript.info, and DevDocs. If you need authoritative detail, MDN is the better choice; if you only want to quickly check whether a method mutates, this site is more lightweight.