ngx-signal-combinators

Composable boolean helpers built on Angular 20+ signals. The library exports tree-shakable utilities that let you combine Signal<boolean> values just like boolean expressions, while maintaining full type safety and reactivity.

Installation

npm install ngx-signal-combinators

The package is designed for Angular 20+ applications that leverage the standalone APIs.

Usage

API surface

| Function | Description | | --- | --- | | and(...signals) | Returns a computed signal that is true when every source signal is currently true (empty input resolves to true). | | or(...signals) | Returns a computed signal that is true when any source signal is currently true (empty input resolves to false). | | not(signal) | Returns a computed signal that negates the current value of the supplied signal. | | pr(signal, predicate) | Returns a computed signal that runs the predicate against the current value of the supplied signal. |

Template example

Below are individual template snippets that demonstrate each helper (assuming the component exposes isSignedIn, hasPremium, isSuspended, searchTerm, and a predicate helper isNonEmpty as signals/functions):

and(...)

@if (and(isSignedIn, hasPremium)()) {
  <article class="premium-banner">
    Thanks for subscribing! Premium features unlocked.
  </article>
} @else {
  <article class="premium-banner--locked">Activate premium to unlock more features.</article>
}

not(...)

@if (not(isSuspended)()) {
  <aside class="account-status">Account in good standing.</aside>
} @else {
  <aside class="account-status--warning">Account currently suspended.</aside>
}

or(...)

@if (or(isSignedIn, hasPremium)()) {
  <section class="dashboard">Dashboard available.</section>
} @else {
  <section class="dashboard--locked">Sign in to access your dashboard.</section>
}

pr(...)

@if (pr(searchTerm, isNonEmpty)()) {
  <section class="search-results">
    Showing results for "{{ searchTerm() }}".
  </section>
} @else {
  <section class="search-results--empty">
    Enter a search term to see results.
  </section>
}

Testing

Unit tests are provided in tests/ngx-signal-combinators.spec.ts using Vitest. They verify every exported helper. Run them with:

npx vitest run

The tests assert that each computed signal reacts to updates emitted by the source signals. If you prefer a browser-like environment, enable the jsdom environment in your Vitest config.