It appears you have a well-structured Git repository with various files, including SVG icons and HTML documents. Here's a brief overview:

backend/node_modules/date-fns/getOverlappingDaysInIntervals/index.js

@@ -0,0 +1,66 @@
+"use strict";
+
+var _interopRequireDefault = require("@babel/runtime/helpers/interopRequireDefault").default;
+Object.defineProperty(exports, "__esModule", {
+  value: true
+});
+exports.default = getOverlappingDaysInIntervals;
+var _index = _interopRequireDefault(require("../toDate/index.js"));
+var _index2 = _interopRequireDefault(require("../_lib/requiredArgs/index.js"));
+var MILLISECONDS_IN_DAY = 24 * 60 * 60 * 1000;
+
+/**
+ * @name getOverlappingDaysInIntervals
+ * @category Interval Helpers
+ * @summary Get the number of days that overlap in two time intervals
+ *
+ * @description
+ * Get the number of days that overlap in two time intervals
+ *
+ * @param {Interval} intervalLeft - the first interval to compare. See [Interval]{@link docs/Interval}
+ * @param {Interval} intervalRight - the second interval to compare. See [Interval]{@link docs/Interval}
+ * @returns {Number} the number of days that overlap in two time intervals
+ * @throws {TypeError} 2 arguments required
+ * @throws {RangeError} The start of an interval cannot be after its end
+ * @throws {RangeError} Date in interval cannot be `Invalid Date`
+ *
+ * @example
+ * // For overlapping time intervals adds 1 for each started overlapping day:
+ * getOverlappingDaysInIntervals(
+ *   { start: new Date(2014, 0, 10), end: new Date(2014, 0, 20) },
+ *   { start: new Date(2014, 0, 17), end: new Date(2014, 0, 21) }
+ * )
+ * //=> 3
+ *
+ * @example
+ * // For non-overlapping time intervals returns 0:
+ * getOverlappingDaysInIntervals(
+ *   { start: new Date(2014, 0, 10), end: new Date(2014, 0, 20) },
+ *   { start: new Date(2014, 0, 21), end: new Date(2014, 0, 22) }
+ * )
+ * //=> 0
+ */
+
+function getOverlappingDaysInIntervals(dirtyIntervalLeft, dirtyIntervalRight) {
+  (0, _index2.default)(2, arguments);
+  var intervalLeft = dirtyIntervalLeft || {};
+  var intervalRight = dirtyIntervalRight || {};
+  var leftStartTime = (0, _index.default)(intervalLeft.start).getTime();
+  var leftEndTime = (0, _index.default)(intervalLeft.end).getTime();
+  var rightStartTime = (0, _index.default)(intervalRight.start).getTime();
+  var rightEndTime = (0, _index.default)(intervalRight.end).getTime();
+
+  // Throw an exception if start date is after end date or if any date is `Invalid Date`
+  if (!(leftStartTime <= leftEndTime && rightStartTime <= rightEndTime)) {
+    throw new RangeError('Invalid interval');
+  }
+  var isOverlapping = leftStartTime < rightEndTime && rightStartTime < leftEndTime;
+  if (!isOverlapping) {
+    return 0;
+  }
+  var overlapStartDate = rightStartTime < leftStartTime ? leftStartTime : rightStartTime;
+  var overlapEndDate = rightEndTime > leftEndTime ? leftEndTime : rightEndTime;
+  var differenceInMs = overlapEndDate - overlapStartDate;
+  return Math.ceil(differenceInMs / MILLISECONDS_IN_DAY);
+}
+module.exports = exports.default;