Don't remove digits and _ from slot names

src/utils/names.ts

@@ -111,5 +111,5 @@ export function quote_prop_if_necessary(name: string) {
 }
 
 export function sanitize(name: string) {
-	return name.replace(/[^a-zA-Z]+/g, '_').replace(/^_/, '').replace(/_$/, '');
-}
+	return name.replace(/[^a-zA-Z0-9_]+/g, '_').replace(/^_/, '').replace(/_$/, '');
+}

test/js/samples/slot-names/expected.js

@@ -0,0 +1,121 @@
+/* generated by Svelte vX.Y.Z */
+import {
+	SvelteComponent as SvelteComponent_1,
+	append,
+	create_slot,
+	detach,
+	element,
+	get_slot_changes,
+	get_slot_context,
+	init,
+	insert,
+	noop,
+	safe_not_equal,
+	space
+} from "svelte/internal";
+
+function create_fragment(ctx) {
+	var div, t0, t1;
+
+	const header_1_slot_1 = ctx.$$slot_header_1;
+	const header_1_slot = create_slot(header_1_slot_1, ctx, null);
+
+	const header_2__slot_1 = ctx.$$slot_header_2_;
+	const header_2__slot = create_slot(header_2__slot_1, ctx, null);
+
+	const header_3_slot_1 = ctx.$$slot_header_3;
+	const header_3_slot = create_slot(header_3_slot_1, ctx, null);
+
+	return {
+		c() {
+			div = element("div");
+
+			if (header_1_slot) header_1_slot.c();
+			t0 = space();
+
+			if (header_2__slot) header_2__slot.c();
+			t1 = space();
+
+			if (header_3_slot) header_3_slot.c();
+		},
+
+		l(nodes) {
+			if (header_1_slot) header_1_slot.l(div_nodes);
+			if (header_2__slot) header_2__slot.l(div_nodes);
+			if (header_3_slot) header_3_slot.l(div_nodes);
+		},
+
+		m(target, anchor) {
+			insert(target, div, anchor);
+
+			if (header_1_slot) {
+				header_1_slot.m(div, null);
+			}
+
+			append(div, t0);
+
+			if (header_2__slot) {
+				header_2__slot.m(div, null);
+			}
+
+			append(div, t1);
+
+			if (header_3_slot) {
+				header_3_slot.m(div, null);
+			}
+		},
+
+		p(changed, ctx) {
+			if (header_1_slot && header_1_slot.p && changed.$$scope) {
+				header_1_slot.p(get_slot_changes(header_1_slot_1, ctx, changed,), get_slot_context(header_1_slot_1, ctx, null));
+			}
+
+			if (header_2__slot && header_2__slot.p && changed.$$scope) {
+				header_2__slot.p(get_slot_changes(header_2__slot_1, ctx, changed,), get_slot_context(header_2__slot_1, ctx, null));
+			}
+
+			if (header_3_slot && header_3_slot.p && changed.$$scope) {
+				header_3_slot.p(get_slot_changes(header_3_slot_1, ctx, changed,), get_slot_context(header_3_slot_1, ctx, null));
+			}
+		},
+
+		i: noop,
+		o: noop,
+
+		d(detaching) {
+			if (detaching) {
+				detach(div);
+			}
+
+			if (header_1_slot) header_1_slot.d(detaching);
+
+			if (header_2__slot) header_2__slot.d(detaching);
+
+			if (header_3_slot) header_3_slot.d(detaching);
+		}
+	};
+}
+
+function instance($$self, $$props, $$invalidate) {
+	let { $$slot_header_1, $$slot_header_2_, $$slot_header_3, $$scope } = $$props;
+
+	$$self.$set = $$props => {
+		if ('$$scope' in $$props) $$invalidate('$$scope', $$scope = $$props.$$scope);
+	};
+
+	return {
+		$$slot_header_1,
+		$$slot_header_2_,
+		$$slot_header_3,
+		$$scope
+	};
+}
+
+class SvelteComponent extends SvelteComponent_1 {
+	constructor(options) {
+		super();
+		init(this, options, instance, create_fragment, safe_not_equal, []);
+	}
+}
+
+export default SvelteComponent;

test/js/samples/slot-names/input.svelte

@@ -0,0 +1,5 @@
+<div>
+	<slot name="_header-1" />
+	<slot name="header-2_-" />
+	<slot name="-header-3-" />
+</div>