2 files changed, 94 insertions, 0 deletions
diff --git a/datetime/mod.ts b/datetime/mod.ts
new file mode 100644
index 000000000..db66af177
--- /dev/null
+++ b/datetime/mod.ts
@@ -0,0 +1,70 @@
+/**
+ * Parse date from string using format string
+ *
+ * @param {string} dateStr - date string
+ * @param {string} format - format string
+ * @return {Date} Parsed date
+ */
+export function parseDate(dateStr: string, format: string): Date {
+  let m, d, y: string;
+
+  if (format === "mm-dd-yyyy") {
+    const datePattern = /^(\d{2})-(\d{2})-(\d{4})$/;
+    [, m, d, y] = datePattern.exec(dateStr);
+  } else if (format === "dd-mm-yyyy") {
+    const datePattern = /^(\d{2})-(\d{2})-(\d{4})$/;
+    [, d, m, y] = datePattern.exec(dateStr);
+  } else if (format === "yyyy-mm-dd") {
+    const datePattern = /^(\d{4})-(\d{2})-(\d{2})$/;
+    [, y, m, d] = datePattern.exec(dateStr);
+  }
+
+  return new Date(Number(y), Number(m) - 1, Number(d));
+}
+
+/**
+ * Parse date & time from string using format string
+ *
+ * @param {string} dateStr - date & time string
+ * @param {string} format - format string
+ * @return {Date} Parsed date
+ */
+export function parseDateTime(datetimeStr: string, format: string): Date {
+  let m, d, y, ho, mi: string;
+
+  if (format === "mm-dd-yyyy hh:mm") {
+    const datePattern = /^(\d{2})-(\d{2})-(\d{4}) (\d{2}):(\d{2})$/;
+    [, m, d, y, ho, mi] = datePattern.exec(datetimeStr);
+  } else if (format === "dd-mm-yyyy hh:mm") {
+    const datePattern = /^(\d{2})-(\d{2})-(\d{4}) (\d{2}):(\d{2})$/;
+    [, d, m, y, ho, mi] = datePattern.exec(datetimeStr);
+  } else if (format === "yyyy-mm-dd hh:mm") {
+    const datePattern = /^(\d{4})-(\d{2})-(\d{2}) (\d{2}):(\d{2})$/;
+    [, y, m, d, ho, mi] = datePattern.exec(datetimeStr);
+  } else if (format === "hh:mm mm-dd-yyyy") {
+    const datePattern = /^(\d{2})-(\d{2})-(\d{4}) (\d{2}):(\d{2})$/;
+    [, ho, mi, m, d, y] = datePattern.exec(datetimeStr);
+  } else if (format === "hh:mm dd-mm-yyyy") {
+    const datePattern = /^(\d{2})-(\d{2})-(\d{4}) (\d{2}):(\d{2})$/;
+    [, ho, mi, d, m, y] = datePattern.exec(datetimeStr);
+  } else if (format === "hh:mm yyyy-mm-dd") {
+    const datePattern = /^(\d{4})-(\d{2})-(\d{2}) (\d{2}):(\d{2})$/;
+    [, ho, mi, y, m, d] = datePattern.exec(datetimeStr);
+  }
+
+  return new Date(Number(y), Number(m) - 1, Number(d), Number(ho), Number(mi));
+}
+
+/**
+ * Get number of current day in year
+ *
+ * @return {number} Number of current day in year
+ */
+export function currentDayOfYear(): number {
+  return (
+    Math.ceil(new Date().getTime() / 86400000) -
+    Math.floor(
+      new Date().setFullYear(new Date().getFullYear(), 0, 1) / 86400000
+    )
+  );
+}
diff --git a/datetime/test.ts b/datetime/test.ts
new file mode 100644
index 000000000..d5c1622cc
--- /dev/null
+++ b/datetime/test.ts
@@ -0,0 +1,24 @@
+import { test, assertEqual } from "../testing/mod.ts";
+import * as datetime from "mod.ts";
+
+test(function parseDateTime() {
+  assertEqual(
+    datetime.parseDateTime("01-03-2019 16:34", "mm-dd-yyyy hh:mm"),
+    new Date(2019, 1, 3, 16, 34)
+  );
+});
+test(function parseDate() {
+  assertEqual(
+    datetime.parseDateTime("01-03-2019", "mm-dd-yyyy"),
+    new Date(2019, 1, 3)
+  );
+});
+test(function currentDayOfYear() {
+  assertEqual(
+    datetime.currentDayOfYear(),
+    Math.ceil(new Date().getTime() / 86400000) -
+      Math.floor(
+        new Date().setFullYear(new Date().getFullYear(), 0, 1) / 86400000
+      )
+  );
+});