minWords()
🧭 API map
| I want to… | Details |
|---|---|
| See every accepted call style | Signatures |
| See common and advanced usage | Usage and behavior |
| Customize messages | Message configuration |
| Understand reactive constraints | Reactive behavior |
| Return to the complete catalog | Built-in validators |
📐 Signatures
minWords(minimum)
minWords(minimum, message)
minWords(minimum, options)
Reactive constraint arguments use a zero-argument function. The function may read signals and,
where supported, return undefined to disable the constraint temporarily.
📖 Usage and behavior
Requires a non-empty string to contain at least a number of words:
const myForm = form({
summary: field('', [required, minWords(3)]),
description: field('', [minWords(() => minimumWords())]),
biography: field('', [minWords(3, 'Add more detail.')]),
});
null and '' pass. A reactive minimum returning undefined or NaN disables the constraint. A word is a Unicode letter-or-number sequence that may contain internal apostrophes or hyphens, so L'été and well-known each count as one word. A failure is { kind: 'minWords', minWords, actual, message }, where actual is the observed word count.
💬 Message configuration
Every failure has a default English message. Where supported, pass a string as the final argument or use an options object for a static or reactive message, as shown above.
A message function may read signals. Returning undefined continues through node, Angular
provider, process-wide, and built-in message fallbacks. See
Validator messages.
⚡ Reactive behavior
The options object accepts a reactive when predicate. Signals read from its validator context are
tracked; while it returns false, the rule contributes neither errors nor constraint metadata.
const requireDetailedSummary = signal(false);
const summary = field('Too short', [
minWords(20, { when: () => requireDetailedSummary() })
]);
Reactive constraint functions and message functions track the signals they read. When a resolved constraint becomes unavailable, validators that support optional constraint sources temporarily stop contributing their error and metadata.
The validator runs synchronously as part of its node's validator source. Disabled, readonly, and hidden nodes skip validation until they become interactive again.