Hydrate your React components only when you need to

Run build scripts only when files changed

"On demand" caching that kicks in only when requests arrive simultaneously.

> A declarative component for conditional rendering

Easily run npm scripts only when in (or not in) a CI environment.

promake rule for installing node_modules only when necessary

Execute a function only when certain events on certain target element have or have not occured within given timeout.

A pipe utility that lazily evaluates only when needed, and only once.

only-when ===

Dynamically polyfill only when needed by the browser. Complementary to Polyfill.io

Deep state observer is an state management library that will fire listeners only when specified object node (which also can be a wildcard) was changed.

This library allows you to show CSS :hover pseudo-class only when triggered by the mouse.

Define lazy properties on objects that are initialized once and only when accessed. Also known as a lazy initialization and cached/memoized getters.

This library allows you to show CSS :focus pseudo-class only when triggered by the keyboard.

Bundle with browserify only when file changed from last time

Work with Plink, copy assets to destDir folder only when devMode is false

Compile with babel only when file changed from last time.

Javascript show reel, executing a series of callbacks only when the browser is in focus

Encrypt changed dotenvx env files only when plaintext values drift

Dilaya agent-loop CLI — a dumb (AI-free) poller that wakes Claude only when there's work.