docs(std/datetime): document toIMF, isLeap, difference, and constants (#7931)

std/datetime/README.md

@@ -32,6 +32,8 @@ are supported:
 - `'foo'` - quoted literal.
 - `./-` - unquoted literal.
 
+## Methods
+
 ### parse
 
 Takes an input `string` and a `formatString` to parse to a `date`.
@@ -85,3 +87,102 @@ import { weekOfYear } from "https://deno.land/std@$STD_VERSION/datetime/mod.ts";
 
 weekOfYear(new Date("2020-12-28T03:24:00")); // Returns 53
 ```
+
+### toIMF
+
+Formats the given date to IMF date time format. (Reference:
+https://tools.ietf.org/html/rfc7231#section-7.1.1.1 )
+
+```js
+import { toIMF } from "https://deno.land/std@$STD_VERSION/datetime/mod.ts";
+
+toIMF(new Date(0)); // => returns "Thu, 01 Jan 1970 00:00:00 GMT"
+```
+
+### isLeap
+
+Returns true if the given date or year (in number) is a leap year. Returns false
+otherwise.
+
+```js
+import { isLeap } from "https://deno.land/std@$STD_VERSION/datetime/mod.ts";
+
+isLeap(new Date("1970-01-01")); // => returns false
+isLeap(new Date("1972-01-01")); // => returns true
+isLeap(new Date("2000-01-01")); // => returns true
+isLeap(new Date("2100-01-01")); // => returns false
+isLeap(1972); // => returns true
+```
+
+### difference
+
+Returns the difference of the 2 given dates in the given units. If the units are
+omitted, it returns the difference in the all available units.
+
+Available units: "milliseconds", "seconds", "minutes", "hours", "days", "weeks",
+"months", "quarters", "years"
+
+```js
+import { difference } from "https://deno.land/std@$STD_VERSION/datetime/mod.ts";
+
+const date0 = new Date("2018-05-14");
+const date1 = new Date("2020-05-13");
+
+difference(date0, date1, { units: ["days", "months", "years"] });
+// => returns { days: 730, months: 23, years: 1 }
+
+difference(date0, date1);
+// => returns {
+//   milliseconds: 63072000000,
+//   seconds: 63072000,
+//   minutes: 1051200,
+//   hours: 17520,
+//   days: 730,
+//   weeks: 104,
+//   months: 23,
+//   quarters: 5,
+//   years: 1
+// }
+```
+
+## Constants
+
+### SECOND
+
+```
+import { SECOND } from "https://deno.land/std@$STD_VERSION/datetime/mod.ts";
+
+console.log(SECOND); // => 1000
+```
+
+### MINUTE
+
+```
+import { MINUTE } from "https://deno.land/std@$STD_VERSION/datetime/mod.ts";
+
+console.log(MINUTE); // => 60000 (60 * 1000)
+```
+
+### HOUR
+
+```
+import { HOUR } from "https://deno.land/std@$STD_VERSION/datetime/mod.ts";
+
+console.log(HOUR); // => 3600000 (60 * 60 * 1000)
+```
+
+### DAY
+
+```
+import { DAY } from "https://deno.land/std@$STD_VERSION/datetime/mod.ts";
+
+console.log(DAY); // => 86400000 (24 * 60 * 60 * 1000)
+```
+
+### WEEK
+
+```
+import { WEEK } from "https://deno.land/std@$STD_VERSION/datetime/mod.ts";
+
+console.log(WEEK); // => 604800000 (7 * 24 * 60 * 60 * 1000)
+```