feat(timeSince): time elapsed since in xx days/hours/minutes ago format (#217)

Author: sumdook

src/index.js

@@ -80,6 +80,7 @@ import descendingOrder from './descending-order'
 import reduceCount from './reduceCount'
 import BitwiseAnd from './BitwiseAnd'
 import copyArrayByValue from './copyArrayByValue'
+import timeSince from './timeSince'
 
 export {
   reverseArrayInPlace,
@@ -164,4 +165,5 @@ export {
   reduceCount,
   BitwiseAnd,
   copyArrayByValue,
+  timeSince,
 }

src/timeSince.js

@@ -0,0 +1,25 @@
+export default timeSince
+
+/**
+ * This method will return time ellapse since in "xxxx days/hours/mins/seconds ago" format.
+ * Inspired by: https://stackoverflow.com/a/3177838/8301717
+ * @param {Date} date - The date object
+ * @return {String} - Formatted time
+ */
+
+function timeSince(date) {
+  const seconds = Math.floor((new Date() - date) / 1000)
+  let interval = Math.floor(seconds / 86400)
+  if (interval > 1) {
+    return `${interval} days ago`
+  }
+  interval = Math.floor(seconds / 3600)
+  if (interval > 1) {
+    return `${interval} hours ago`
+  }
+  interval = Math.floor(seconds / 60)
+  if (interval > 1) {
+    return `${interval} minutes ago`
+  }
+  return `${Math.floor(seconds)} seconds ago`
+}

test/timeSince.test.js

@@ -0,0 +1,31 @@
+import test from 'ava'
+import {timeSince} from '../src'
+
+test('Changes date to days ago format', t => {
+  const aDay = 2 * 24 * 60 * 60 * 1000
+  const expected = '2 days ago'
+  const actual = timeSince(new Date(Date.now() - aDay))
+  t.deepEqual(actual, expected)
+})
+
+test('Changes date to hours ago format', t => {
+  const threeHours = 3 * 60 * 60 * 1000
+  const expected = '3 hours ago'
+  const actual = timeSince(new Date(Date.now() - threeHours))
+  t.deepEqual(actual, expected)
+})
+  
+
+test('Changes date to minute ago format', t => {
+  const fourMinutes = 4 * 60 * 1000
+  const expected = '4 minutes ago'
+  const actual = timeSince(new Date(Date.now() - fourMinutes))
+  t.deepEqual(actual, expected)
+})
+
+test('Changes date to seconds ago format', t => {
+  const fiveSeconds = 5 * 1000
+  const expected = '5 seconds ago'
+  const actual = timeSince(new Date(Date.now() - fiveSeconds))
+  t.deepEqual(actual, expected)
+})