Allow parseJSON to accept strings without a trailing 'Z' symbold an…

…d with up to 6 digits in the milliseconds field (date-fns#1463)

src/parseJSON/index.js

@@ -17,6 +17,9 @@ import toDate from '../toDate/index.js'
  *     - `2000-03-15T05:20:10Z`: Without milliseconds
  *     - `2000-03-15T05:20:10+00:00`: With a zero offset, the default JSON encoded format in some other languages
  *     - `2000-03-15T05:20:10+0000`: With a zero offset without a colon
+ *     - `2000-03-15T05:20:10`: Without a trailing 'Z' symbol
+ *     - `2000-03-15T05:20:10.134566`: Up to 6 digits in milliseconds field. Only first 3 are taken into account
+ *          since JS does now allow fractional milliseconds
  *
  * For convenience and ease of use these other input types are also supported
  * via [toDate]{@link https://date-fns.org/docs/toDate}:
@@ -39,7 +42,7 @@ export default function parseJSON(argument) {
 
   if (typeof argument === 'string') {
     var parts = argument.match(
-      /(\d{4})-(\d{2})-(\d{2})T(\d{2}):(\d{2}):(\d{2})(?:\.(\d{3}))?(?:Z|\+00:?00)/
+      /(\d{4})-(\d{2})-(\d{2})T(\d{2}):(\d{2}):(\d{2})(?:\.(\d{3})\d{0,3})?(?:Z|\+00:?00)?/
     )
     if (parts) {
       return new Date(

src/parseJSON/test.js

@@ -32,6 +32,20 @@ describe('parseJSON', function() {
     assert.equal(parsedDate.toISOString(), expectedDate)
   })
 
+  it('parses a fully formed ISO date without Z', () => {
+    const date = '2000-03-15T05:20:10.123'
+    const expectedDate = '2000-03-15T05:20:10.123Z'
+    const parsedDate = parseJSON(date)
+    assert.equal(parsedDate.toISOString(), expectedDate)
+  })
+
+  it('parses a fully formed ISO date without Z and with 6-digit millisecond part', () => {
+    const date = '2000-03-15T05:20:10.123456'
+    const expectedDate = '2000-03-15T05:20:10.123Z'
+    const parsedDate = parseJSON(date)
+    assert.equal(parsedDate.toISOString(), expectedDate)
+  })
+
   it('clones a date object', () => {
     const date = new Date(2000, 2, 15, 5, 20, 10, 20)
     const parsedDate = parseJSON(date)