Replace date-fns for hand-rolled date formatting

Closes #443
Fixes #436

README.md

@@ -115,7 +115,7 @@ Check out documentation and other usage examples in the [`docs` directory](./doc
     Anything else means all processes should exit successfully.
   - `restartTries`: how many attempts to restart a process that dies will be made. Default: `0`.
   - `restartDelay`: how many milliseconds to wait between process restarts. Default: `0`.
-  - `timestampFormat`: a [date-fns format](https://date-fns.org/v2.0.1/docs/format)
+  - `timestampFormat`: a [Unicode format](https://www.unicode.org/reports/tr35/tr35-dates.html#Date_Field_Symbol_Table)
     to use when prefixing with `time`. Default: `yyyy-MM-dd HH:mm:ss.ZZZ`
   - `additionalArguments`: list of additional arguments passed that will get replaced in each command. If not defined, no argument replacing will happen.
 

bin/concurrently.ts

@@ -164,7 +164,9 @@ const args = yargs(hideBin(process.argv))
         },
         'timestamp-format': {
             alias: 't',
-            describe: 'Specify the timestamp in moment/date-fns format.',
+            describe:
+                'Specify the timestamp in Unicode format:\n' +
+                'https://www.unicode.org/reports/tr35/tr35-dates.html#Date_Field_Symbol_Table',
             default: defaults.timestampFormat,
             type: 'string',
         },

declarations/intl.d.ts

@@ -0,0 +1,21 @@
+/* eslint-disable @typescript-eslint/no-explicit-any */
+// TODO: Delete this file once Typescript has added these.
+declare namespace Intl {
+    interface DateTimeFormatPartTypesRegistry {
+        yearName: any;
+        relatedYear: any;
+    }
+
+    /**
+     * @see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl/Locale/getWeekInfo
+     */
+    interface WeekInfo {
+        firstDay: number;
+        weekend: readonly number[];
+        minimalDays: number;
+    }
+
+    interface Locale {
+        readonly weekInfo: WeekInfo;
+    }
+}

package.json

@@ -57,7 +57,6 @@
   "license": "MIT",
   "dependencies": {
     "chalk": "^4.1.2",
-    "date-fns": "^2.30.0",
     "lodash": "^4.17.21",
     "rxjs": "^7.8.1",
     "shell-quote": "^1.8.1",