Add calculateRemainingMilliseconds() helper function

1 files changed, 12 insertions, 0 deletions

diff --git a/app/assets/javascripts/lib/utils/datetime_utility.js b/app/assets/javascripts/lib/utils/datetime_utility.js
index 1bdf98d0c97..46740308f17 100644
--- a/app/assets/javascripts/lib/utils/datetime_utility.js
+++ b/app/assets/javascripts/lib/utils/datetime_utility.js
@@ -473,3 +473,15 @@ export const stringifyTime = timeObject => {
  */
 export const abbreviateTime = timeStr =>
   timeStr.split(' ').filter(unitStr => unitStr.charAt(0) !== '0')[0];
+
+/**
+ * Calculates the milliseconds between now and a given date string.
+ * The result cannot become negative.
+ *
+ * @param endDate date string that the time difference is calculated for
+ * @return {number} number of milliseconds remaining until the given date
+ */
+export const calculateRemainingMilliseconds = endDate => {
+  const remainingMilliseconds = new Date(endDate).getTime() - Date.now();
+  return Math.max(remainingMilliseconds, 0);
+};