Resolve #2629 (#2630)

src/mfm/html.ts

@@ -4,10 +4,7 @@ const { JSDOM } = jsdom;
 import config from '../config';
 import { INote } from '../models/note';
 import { TextElement } from './parse';
-
-function intersperse<T>(sep: T, xs: T[]): T[] {
-	return [].concat(...xs.map(x => [sep, x])).slice(1);
-}
+import { intersperse } from '../prelude/array';
 
 const handlers: { [key: string]: (window: any, token: any, mentionedRemoteUsers: INote['mentionedRemoteUsers']) => void } = {
 	bold({ document }, { bold }) {

src/prelude/array.ts

@@ -5,3 +5,7 @@ export function countIf<T>(f: (x: T) => boolean, xs: T[]): number {
 export function count<T>(x: T, xs: T[]): number {
 	return countIf(y => x === y, xs);
 }
+
+export function intersperse<T>(sep: T, xs: T[]): T[] {
+	return [].concat(...xs.map(x => [sep, x])).slice(1);
+}