feat(pat scroll-marker): Implement selector option.

Define the CSS selector which is used to find navigation links with hash
URLs. The default is "a[href^='#']" which would find all anchor elements
which href starts with a "#" sign.

Author: thet

src/pat/scroll-marker/documentation.md

@@ -56,4 +56,5 @@ Here is a complete example:
 | side                  | `top`          | `top`, `bottom`, `middle`, `auto`        | Side of element that scrolls. This is used to calculate the current item. The defined side of the element will be used to calculate the distance baseline. If this is set to "auto" then one of the "top" or "bottom" positions are used, depending on which one is nearer to the distance baseline. |
 | distance              | `50%`          | CSS length (px, %, vw, vh, vmin or vmax) | Distance from side of scroll box. any amount in px, %, vw, vh, vmin or vmax. This is used to calculate the current item. The nearest element to the distance-baseline measured from the top of the container will get the current class. |
 | visibility            |                | `none`, `most-visible`                   | Visibility of element in scroll box. This is used to calculate the current item. If "most-visible" is set, the element which is most visible in the scroll container gets the current class. If more elements have the same visibility ratio, the other conditions are used to calculate the current one. |
+| selector              | `a[href^='#']` | CSS selector, `none`                     | Selects the element within the pat-navigation container that should get a class current while scrolling, when applicable. |
 

src/pat/scroll-marker/scroll-marker.js

@@ -16,6 +16,7 @@ parser.addArgument("current-content-class", "scroll-marker-current");
 parser.addArgument("side", "top", ["top", "bottom", "middle", "auto"]);
 parser.addArgument("distance", "50%");
 parser.addArgument("visibility", null, [null, "none", "most-visible"]);
+parser.addArgument("selector", "a[href^='#']");
 
 class Pattern extends BasePattern {
     static name = "scroll-marker";
@@ -31,7 +32,7 @@ class Pattern extends BasePattern {
     init() {
         // Get all elements that are referenced by links in the current page.
         this.observables = new Map(
-            [...dom.querySelectorAllAndMe(this.el, "a[href^='#']")]
+            [...dom.querySelectorAllAndMe(this.el, this.options.selector)]
                 .map(
                     // Create the structure:
                     // id: {link, target}

src/pat/scroll-marker/scroll-marker.test.js

@@ -232,6 +232,30 @@ describe("pat-scroll-marker", () => {
             expect(id2.classList.contains("scroll-marker-current")).toBe(true);
             expect(id3.classList.contains("scroll-marker-current")).toBe(false);
         });
+
+        it("1.5: The selector option can exclude some items", async () => {
+            // With the selector option you can include/exclude some items from
+            // being included in the scroll-marker functionality.
+
+            const { nav_id1, nav_id2, nav_id3, id1, id2, id3 } =
+                await create_scroll_marker({
+                    options: {
+                        selector: "a[href^='#']:not([href='#id3'])",
+                    },
+                });
+
+            expect(nav_id1.classList.contains("in-view")).toBe(false);
+            expect(nav_id2.classList.contains("in-view")).toBe(true);
+            expect(nav_id3.classList.contains("in-view")).toBe(false);
+
+            expect(nav_id1.classList.contains("current")).toBe(false);
+            expect(nav_id2.classList.contains("current")).toBe(true);
+            expect(nav_id3.classList.contains("current")).toBe(false);
+
+            expect(id1.classList.contains("scroll-marker-current")).toBe(false);
+            expect(id2.classList.contains("scroll-marker-current")).toBe(true);
+            expect(id3.classList.contains("scroll-marker-current")).toBe(false);
+        });
     });
 
     describe("2: Test on element as scroll container", () => {