use esm import/export

MIGRATION.md

@@ -1,4 +1,17 @@
 # Migration Guide
 
+## Migrating from v3 to v4
+o-date is an esm module now, so if you are using commonjs you'll want to import it like this:
+
+```js
+let ODate = require("o-date").default // note the .default
+```
+esm users can import it as so:
+
+```js
+import ODate from "o-date"
+```
+
+
 ## Migrating from v2 to v3
 We removed the ability to use o-date on the server in v3, the npm package `@financial-times/ft-date-format` is the server version of o-date, it is a drop-in replacement for o-date's server use.

README.md

@@ -34,9 +34,15 @@ document.addEventListener('DOMContentLoaded', function() {
 });
 ```
 
-You can also run `require('o-date').init()` once the DOM has loaded if you don't want to initialise other modules at the same time.
+You can also import `o-date` as a module.
 
-Run `require('o-date').init(el)` on any elements containing dates that are added to the page after DOM load, and if you keep a reference to the returned object you can clean them up with `oDateItem.destroy()` to stop processing.
+```
+import ODate from 'o-date'
+```
+
+You can run `ODate.init()` once the DOM has loaded if you don't want to initialise other modules at the same time.
+
+Run `ODate.init(el)` on any elements containing dates that are added to the page after DOM load, and if you keep a reference to the returned object you can clean them up with `oDateItem.destroy()` to stop processing.
 
 #### o-date#format(date, tpl)
 

main.js

@@ -1,9 +1,9 @@
-const ftDateFormat = require('ft-date-format');
+import ftDateFormat from 'ft-date-format';
 
 const updateEventName = 'oDate.update';
 let interval;
 
-function ODate(rootEl) {
+export default function ODate(rootEl) {
 	if (!rootEl) {
 		rootEl = document.body;
 	} else if (!(rootEl instanceof HTMLElement)) {
@@ -145,5 +145,3 @@ const constructAll = function() {
 if (typeof window !== 'undefined') {
 	document.addEventListener('o.DOMContentLoaded', constructAll);
 }
-
-module.exports = ODate;