Merge pull request #1369 from RanadeepPolavarapu/feat/tzAwareISO8601

feat: add getISO8601StringTzAware snippet

snippets/toISOStringWithTimezone.md

@@ -0,0 +1,30 @@
+---
+title: toISOStringWithTimezone
+tags: date,math,intermediate
+---
+
+Returns a string in simplified extended ISO format (ISO 8601), including timezone offset.
+
+- Use `Date.prototype.getTimezoneOffset()` to get the timezone offset and reverse it, storing its sign in `diff`.
+- Define a helper function, `pad`, that normalizes any passed number to an integer using `Math.floor()` and `Math.abs()` and pads it to 2 digits, using `String.prototype.padStart()`.
+- Use `pad` and the built-in methods in the `Date` prototype to build the ISO 8601 string with timezone offset.
+
+```js
+const toISOStringWithTimezone = date => {
+  const tzOffset = -date.getTimezoneOffset();
+  const diff = tzOffset >= 0 ? '+' : '-';
+  const pad = n => `${Math.floor(Math.abs(n))}`.padStart(2, '0');
+  return date.getFullYear() +
+    '-' + pad(date.getMonth() + 1) +
+    '-' + pad(date.getDate()) +
+    'T' + pad(date.getHours()) +
+    ':' + pad(date.getMinutes()) +
+    ':' + pad(date.getSeconds()) +
+    diff + pad(tzOffset / 60) +
+    ':' + pad(tzOffset % 60);
+};
+```
+
+```js
+toISOStringWithTimezone(new Date()); // "2020-10-06T20:43:33-04:00"
+```