feat: rule.if

README.md

@@ -235,6 +235,12 @@ Using this option, you can re-enable it for selected visits:
 
 Optional, Type: `boolean | string` – If you have [Accessibility Plugin](https://github.com/swup/a11y-plugin/) installed, you can adjust which element to focus for the visit [as described here](https://github.com/swup/a11y-plugin/#visita11yfocus).
 
+#### rule.if
+
+Optional, Type: `(visit) => boolean` – Provide a predicate function for fine-grained control over the matching behavior of a rule.
+
+A predicate function that allows for fine-grained control over the matching behavior of a rule. This function receives the current [visit](https://swup.js.org/visit/) as a parameter, and must return a boolean value. If the function returns `false`, the rule is being skipped for the current visit, even if it matches the current route.
+
 ### debug
 
 Type: `boolean`. Set to `true` for debug information in the console. Defaults to `false`.

src/SwupFragmentPlugin.ts

@@ -11,6 +11,7 @@ import {
 import type { Options, Rule, Route, FragmentVisit } from './inc/defs.js';
 import * as handlers from './inc/handlers.js';
 import { __DEV__ } from './inc/env.js';
+import type { Visit } from 'swup';
 
 type RequireKeys<T, K extends keyof T> = Partial<T> & Pick<T, K>;
 type InitOptions = RequireKeys<Options, 'rules'>;
@@ -84,47 +85,64 @@ export default class SwupFragmentPlugin extends PluginBase {
 		cleanupFragmentElements();
 	}
 
+	/**
+	 * Set completely new rules
+	 *
+	 * @access public
+	 */
 	setRules(rules: Rule[]) {
 		this._rawRules = cloneRules(rules);
 		this._parsedRules = rules.map((rule) => this.parseRule(rule));
 		if (__DEV__) this.logger?.log('Updated fragment rules', this.getRules());
 	}
 
+	/**
+	 * Get a clone of the current rules
+	 *
+	 * @access public
+	 */
 	getRules() {
 		return cloneRules(this._rawRules);
 	}
 
+	/**
+	 * Prepend a rule to the existing rules
+	 *
+	 * @access public
+	 */
 	prependRule(rule: Rule) {
 		this.setRules([rule, ...this.getRules()]);
 	}
 
+	/**
+	 * Append a rule to the existing rules
+	 *
+	 * @access public
+	 */
 	appendRule(rule: Rule) {
 		this.setRules([...this.getRules(), rule]);
 	}
 
 	/**
-	 * Add a fragment rule
-	 * @param {Rule} rule 			The rule options
-	 * @param {'start' | 'end'} at 	Should the rule be added to the beginning or end of the existing rules?
+	 * Parse a rule (for e.g. debugging)
+	 *
+	 * @access public
 	 */
-	parseRule({ from, to, containers, name, scroll, focus }: Rule): ParsedRule {
+	parseRule(rule: Rule): ParsedRule {
 		return new ParsedRule({
-			from,
-			to,
-			containers,
-			name,
-			scroll,
-			focus,
+			...rule,
 			logger: this.logger,
 			swup: this.swup
 		});
 	}
 
 	/**
 	 * Get the fragment visit object for a given route
+	 *
+	 * @access public
 	 */
-	getFragmentVisit(route: Route): FragmentVisit | undefined {
-		const rule = getFirstMatchingRule(route, this.parsedRules);
+	getFragmentVisit(route: Route, visit?: Visit): FragmentVisit | undefined {
+		const rule = getFirstMatchingRule(route, this.parsedRules, visit || this.swup.visit);
 
 		// Bail early if no rule matched
 		if (!rule) return;

src/inc/ParsedRule.ts

@@ -1,18 +1,12 @@
 import { matchPath, classify, Location } from 'swup';
-import type { Swup, Path } from 'swup';
-import type { Route } from './defs.js';
+import type { Swup, Path, Visit } from 'swup';
+import type { Route, Rule, Predicate } from './defs.js';
 import { dedupe, queryFragmentElement } from './functions.js';
 import Logger, { highlight } from './Logger.js';
 import { __DEV__ } from './env.js';
 
-type Options = {
+type Options = Rule & {
 	swup: Swup;
-	from: Path;
-	to: Path;
-	containers: string[];
-	name?: string;
-	scroll?: boolean | string;
-	focus?: boolean | string;
 	logger?: Logger;
 };
 
@@ -31,6 +25,7 @@ export default class ParsedRule {
 	scroll: boolean | string = false;
 	focus?: boolean | string;
 	logger?: Logger;
+	if: Predicate = () => true;
 
 	constructor(options: Options) {
 		this.swup = options.swup;
@@ -41,6 +36,7 @@ export default class ParsedRule {
 		if (options.name) this.name = classify(options.name);
 		if (typeof options.scroll !== 'undefined') this.scroll = options.scroll;
 		if (typeof options.focus !== 'undefined') this.focus = options.focus;
+		if (typeof options.if === 'function') this.if = options.if;
 
 		this.containers = this.parseContainers(options.containers);
 
@@ -103,7 +99,14 @@ export default class ParsedRule {
 	/**
 	 * Checks if a given route matches this rule
 	 */
-	public matches(route: Route): boolean {
+	public matches(route: Route, visit: Visit): boolean {
+		if (!this.if(visit)) {
+			if (__DEV__) {
+				this.logger?.log(`ignoring fragment rule due to custom rule.if:`, this);
+			}
+			return false;
+		}
+
 		const { url: fromUrl } = Location.fromUrl(route.from);
 		const { url: toUrl } = Location.fromUrl(route.to);
 

src/inc/defs.ts

@@ -1,4 +1,4 @@
-import type { Path } from 'swup';
+import type { Path, Visit } from 'swup';
 
 /** Represents a route from one to another URL */
 export type Route = {
@@ -15,6 +15,8 @@ export interface FragmentElement extends HTMLElement {
 	};
 }
 
+export type Predicate = (visit: Visit) => boolean;
+
 /** A fragment rule */
 export type Rule = {
 	from: Path;
@@ -23,6 +25,7 @@ export type Rule = {
 	name?: string;
 	scroll?: boolean | string;
 	focus?: boolean | string;
+	if?: Predicate;
 };
 
 /** The plugin options */

src/inc/functions.ts

@@ -1,5 +1,5 @@
-import { Location } from 'swup';
-import type { Swup, Visit, VisitScroll } from 'swup';
+import Swup, { Location } from 'swup';
+import type { Visit, VisitScroll } from 'swup';
 import type { default as FragmentPlugin } from '../SwupFragmentPlugin.js';
 import type { Route, Rule, FragmentVisit, FragmentElement } from './defs.js';
 import type ParsedRule from './ParsedRule.js';
@@ -230,8 +230,12 @@ export const toggleFragmentVisitClass = (
 /**
  * Get the first matching rule for a given route
  */
-export const getFirstMatchingRule = (route: Route, rules: ParsedRule[]): ParsedRule | undefined => {
-	return rules.find((rule) => rule.matches(route));
+export const getFirstMatchingRule = (
+	route: Route,
+	rules: ParsedRule[],
+	visit: Visit
+): ParsedRule | undefined => {
+	return rules.find((rule) => rule.matches(route, visit));
 };
 
 /**
@@ -392,3 +396,12 @@ export function cloneRules(rules: Rule[]): Rule[] {
 		containers: [...rule.containers]
 	}));
 }
+
+/**
+ * Create a visit object for tests
+ */
+export function stubVisit(options: { from?: string; to: string }) {
+	const swup = new Swup();
+	// @ts-expect-error swup.createVisit is protected
+	return swup.createVisit(options);
+}

src/inc/handlers.ts

@@ -22,7 +22,7 @@ export const onLinkToSelf: Handler<'link:self'> = function (this: FragmentPlugin
 	const route = getRoute(visit);
 	if (!route) return;
 
-	const rule = getFirstMatchingRule(route, this.parsedRules);
+	const rule = getFirstMatchingRule(route, this.parsedRules, visit);
 
 	if (rule) visit.scroll.reset = false;
 };
@@ -34,7 +34,7 @@ export const onVisitStart: Handler<'visit:start'> = async function (this: Fragme
 	const route = getRoute(visit);
 	if (!route) return;
 
-	const fragmentVisit = this.getFragmentVisit(route);
+	const fragmentVisit = this.getFragmentVisit(route, visit);
 
 	/**
 	 * Bail early if the current route doesn't match

tests/vitest/ParsedRule.test.ts

@@ -3,6 +3,7 @@ import ParsedRule from '../../src/inc/ParsedRule.js';
 import Logger from '../../src/inc/Logger.js';
 import { spyOnConsole, stubGlobalDocument } from './inc/helpers.js';
 import Swup from 'swup';
+import { stubVisit } from '../../src/inc/functions.js';
 
 describe('ParsedRule', () => {
 	afterEach(() => {
@@ -93,12 +94,18 @@ describe('ParsedRule', () => {
 			from: '/users/',
 			to: '/user/:slug',
 			containers: ['#fragment-1'],
-			swup: new Swup()
+			swup: new Swup(),
+			if: (visit) => true
 		});
-		expect(rule.matches({ from: '/users/', to: '/user/jane' })).toBe(true);
-		expect(rule.matches({ from: '/users/', to: '/users/' })).toBe(false);
-		expect(rule.matches({ from: '/user/jane', to: '/users/' })).toBe(false);
-		expect(rule.matches({ from: '/user/jane', to: '/user/john' })).toBe(false);
+		const visit = stubVisit({ to: '' });
+		expect(rule.matches({ from: '/users/', to: '/user/jane' }, visit)).toBe(true);
+		expect(rule.matches({ from: '/users/', to: '/users/' }, visit)).toBe(false);
+		expect(rule.matches({ from: '/user/jane', to: '/users/' }, visit)).toBe(false);
+		expect(rule.matches({ from: '/user/jane', to: '/user/john' }, visit)).toBe(false);
+
+		/** Respect rule.if */
+		rule.if = (visit) => false;
+		expect(rule.matches({ from: '/users/', to: '/user/jane' }, visit)).toBe(false);
 	});
 
 	it('should validate selectors if matching a rule', () => {
@@ -110,17 +117,18 @@ describe('ParsedRule', () => {
 			swup: new Swup(),
 			logger: new Logger()
 		});
+		const visit = stubVisit({ to: '' });
 
 		/** fragment element missing */
 		stubGlobalDocument(/*html*/ `<div id="swup" class="transition-main"></div>`);
-		expect(rule.matches({ from: '/foo/', to: '/bar/' })).toBe(false);
+		expect(rule.matches({ from: '/foo/', to: '/bar/' }, visit)).toBe(false);
 		expect(console.error).toBeCalledWith(new Error('skipping rule since #fragment-1 doesn\'t exist in the current document'), expect.any(Object)) // prettier-ignore
 
 		/** fragment element outside of swup's default containers */
 		stubGlobalDocument(
 			/*html*/ `<div id="swup" class="transition-main"></div><div id="fragment-1"></div>`
 		);
-		expect(rule.matches({ from: '/foo/', to: '/bar/' })).toBe(false);
+		expect(rule.matches({ from: '/foo/', to: '/bar/' }, visit)).toBe(false);
 		expect(console.error).toBeCalledWith(new Error('skipping rule since #fragment-1 is outside of swup\'s default containers'), expect.any(Object)) // prettier-ignore
 	});
 });

tests/vitest/adjustVisitScroll.test.ts

@@ -1,11 +1,10 @@
 import { describe, expect, it } from 'vitest';
-import { adjustVisitScroll } from '../../src/inc/functions.js';
+import { adjustVisitScroll, stubVisit } from '../../src/inc/functions.js';
 import Swup from 'swup';
 
 describe('adjustVisitScroll()', () => {
 	it('adjust visit.scroll', () => {
-		// @ts-expect-error
-		const { scroll } = new Swup().createVisit({ to: '' });
+		const { scroll } = stubVisit({ to: '' });
 
 		expect(adjustVisitScroll({ containers: [], scroll: true }, scroll)).toEqual({
 			reset: true

tests/vitest/getRoute.test.ts

@@ -1,24 +1,19 @@
 import { describe, expect, it } from 'vitest';
-import { getRoute } from '../../src/inc/functions.js';
+import { getRoute, stubVisit } from '../../src/inc/functions.js';
 import Swup from 'swup';
 
 describe('getRoute()', () => {
 	it('should get the route from a visit', () => {
-		const swup = new Swup();
 		const route = { from: '/page-1/', to: '/page-2/' };
-		// @ts-expect-error createVisit is protected
-		const visit = swup.createVisit(route);
+		const visit = stubVisit(route);
 		expect(getRoute(visit)).toEqual(route);
 	});
 
 	it('should return undefined for incomplete visits', () => {
-		const swup = new Swup();
-		// @ts-expect-error createVisit is protected
-		const withoutTo = swup.createVisit({ to: '' });
-		expect(getRoute(withoutTo)).toEqual(undefined);
+		const withEmptyTo = stubVisit({ to: '' });
+		expect(getRoute(withEmptyTo)).toEqual(undefined);
 
-		// @ts-expect-error createVisit is protected
-		const withoutFrom = swup.createVisit({ from: '', to: '/page-2/' });
-		expect(getRoute(withoutFrom)).toEqual(undefined);
+		const withEmptyFrom = stubVisit({ from: '', to: '/page-2/' });
+		expect(getRoute(withEmptyFrom)).toEqual(undefined);
 	});
 });