rewrote the Anime.svelte to move out helper functions and clean up code

frontend/src/helperFunctions/convertAniListDateToString.ts

@@ -0,0 +1,17 @@
+import moment from "moment";
+
+export default (date: {
+    year?: number,
+    month?: number,
+    day?: number,
+}): string => {
+    if (date.year === undefined || date.year === 0
+        && date.month === undefined || date.month === 0
+        && date.day === undefined || date.day === 0
+    ) {
+        return ""
+    }
+    const newISODate = new Date(date.year, date.month - 1, date.day)
+    const newMoment = moment(newISODate)
+    return newMoment.format('YYYY-MM-DD')
+}

frontend/src/helperFunctions/convertDateStringToAniList.ts

@@ -0,0 +1,22 @@
+type Date = {
+    year: number,
+    month: number,
+    day: number,
+}
+
+export default (date: string): Date => {
+    if (date === "") {
+        return {
+            year: 0,
+            month: 0,
+            day: 0,
+        }
+    }
+    const re = /^([0-9]{4})-([0-9]{2})-([0-9]{2})/
+    const newDate = re.exec(date)
+    return {
+        year: Number(newDate[1]),
+        month: Number(newDate[2]),
+        day: Number(newDate[3])
+    }
+}