Localize time units on activity heatmap (#21570)

Previously, the months and days were hardcoded into English

* Closes #15541

## Screenshots
### English

![image](https://user-images.githubusercontent.com/20454870/197410352-1b28a637-ce19-41ae-b4e5-27955555b082.png)

### German

![image](https://user-images.githubusercontent.com/20454870/197410455-f243ca84-807f-476e-b8ed-c24e827bfc2d.png)

### Spanish

![image](https://user-images.githubusercontent.com/20454870/197410366-55202ca5-08f9-4152-8f9d-d5eeebd532ef.png)

### Italian

![image](https://user-images.githubusercontent.com/20454870/197410385-75f754dd-e845-4444-8a04-472a8f45b617.png)

### Portuguese
This one has a bit of overflow

![image](https://user-images.githubusercontent.com/20454870/197410414-b91f962e-77e9-4cc7-990b-01c0fc0cbd0b.png)

Signed-off-by: Yarden Shoham <hrsi88@gmail.com>
Co-authored-by: Gusted <williamzijl7@hotmail.com>
Co-authored-by: silverwind <me@silverwind.io>
Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-authored-by: techknowlogick <techknowlogick@gitea.io>

1 files changed, 15 insertions, 0 deletions

diff --git a/web_src/js/utils.js b/web_src/js/utils.js
index 4020b7a7f4..9b8bf925a9 100644
--- a/web_src/js/utils.js
+++ b/web_src/js/utils.js
@@ -70,3 +70,18 @@ export function prettyNumber(num, locale = 'en-US') {
 export function parseUrl(str) {
   return new URL(str, str.startsWith('http') ? undefined : window.location.origin);
 }
+
+// return current locale chosen by user
+function getCurrentLocale() {
+  return document.documentElement.lang;
+}
+
+// given a month (0-11), returns it in the documents language
+export function translateMonth(month) {
+  return new Date(Date.UTC(2022, month, 12)).toLocaleString(getCurrentLocale(), {month: 'short'});
+}
+
+// given a weekday (0-6, Sunday to Saturday), returns it in the documents language
+export function translateDay(day) {
+  return new Date(Date.UTC(2022, 7, day)).toLocaleString(getCurrentLocale(), {weekday: 'short'});
+}