Implement date format for ms and seconds since epoc

README.md

@@ -155,9 +155,14 @@ const template = 'http://example.com/{section|prepend(local_)}'
 
 #### `date(format)`
 Formats a date according to the given date format string.
+
 Uses `date-and-time` under the hood, so refer to
 [their documentation](https://github.com/knowledgecode/date-and-time#formatdateobj-formatstring-utc).
 
+In addition, two custom formats are available: `ms-epoc` and `s-epoc`. They
+format the date as number of microseconds or seconds since 1970-01-01. For
+seconds, microsencods are rounded off to nearest second.
+
 ”Example:
 ```
 const params = {updatedAfter: new Date('2020-03-19T14:08:44Z')}

lib/filters/date-test.js

@@ -86,3 +86,23 @@ test('should return iso string when format is not a string', (t) => {
 
   t.is(ret, expected)
 })
+
+test('should format date as microseconds since epoc', (t) => {
+  const value = new Date('2020-03-18T19:59:03.113Z')
+  const format = 'ms-epoc'
+  const expected = '1584561543113'
+
+  const ret = date(value, format)
+
+  t.is(ret, expected)
+})
+
+test('should format date as seconds since epoc', (t) => {
+  const value = new Date('2020-03-18T19:59:03.113Z')
+  const format = 's-epoc'
+  const expected = '1584561543'
+
+  const ret = date(value, format)
+
+  t.is(ret, expected)
+})

lib/filters/date.js

@@ -13,7 +13,12 @@ function date (value, format) {
   }
   if (isDatish(value) && !Number.isNaN(value.getTime())) {
     if (typeof format === 'string' && format !== '') {
-      return dateTime.format(value, format)
+      if (format.endsWith('s-epoc')) {
+        const ms = value.getTime()
+        return format === 'ms-epoc' ? String(ms) : String(Math.round(ms / 1000))
+      } else {
+        return dateTime.format(value, format)
+      }
     } else {
       return value.toISOString()
     }

tests/filterFunctions-test.js

@@ -37,3 +37,16 @@ test('should generate uri with date filter functions', (t) => {
 
   t.is(uri, expected)
 })
+
+test('should generate uri with date as seconds since epoc', (t) => {
+  const template = 'http://example.com/all{?since=updatedAfter|date(s-epoc)?,until=updatedBefore|date(YYYY-MM-DD)?}'
+  const params = {
+    updatedAfter: new Date('2020-03-20T18:43:11.875Z')
+  }
+  const expected = 'http://example.com/all?since=1584729792'
+
+  const compiled = compile(template)
+  const uri = generate(compiled, params)
+
+  t.is(uri, expected)
+})