Merge pull request #1473 from nhonx/lastDayOfMonth

add lastDateOfMonth

snippets/lastDateOfMonth.md

@@ -0,0 +1,21 @@
+---
+title: lastDateOfMonth
+tags: date,intermediate
+---
+
+Returns the string representation of the last date in the given date's month.
+
+- Use `Date.prototype.getFullYear()`, `Date.prototype.getMonth()` to get the current year and month from the given date.
+- Use the `new Date()` constructor to create a new date with the given year and month incremented by `1`, and the day set to `0` (last day of previous month).
+- Omit the argument, `date`, to use the current date by default.
+
+```js
+const lastDateOfMonth = (date = new Date()) => {
+  let d = new Date(date.getFullYear(), date.getMonth() + 1, 0);
+  return d.toISOString().split('T')[0];
+};
+```
+
+```js
+lastDateOfMonth(new Date('2015-08-11')); // '2015-08-30'
+```