Initial data commit

Task/Find-common-directory-path/JavaScript/find-common-directory-path.js

@@ -0,0 +1,45 @@
+/**
+ * Given an array of strings, return an array of arrays, containing the
+ * strings split at the given separator
+ * @param {!Array<!string>} a
+ * @param {string} sep
+ * @returns {!Array<!Array<string>>}
+ */
+const splitStrings = (a, sep = '/') => a.map(i => i.split(sep));
+
+/**
+ * Given an index number, return a function that takes an array and returns the
+ * element at the given index
+ * @param {number} i
+ * @return {function(!Array<*>): *}
+ */
+const elAt = i => a => a[i];
+
+/**
+ * Transpose an array of arrays:
+ * Example:
+ * [['a', 'b', 'c'], ['A', 'B', 'C'], [1, 2, 3]] ->
+ * [['a', 'A', 1], ['b', 'B', 2], ['c', 'C', 3]]
+ * @param {!Array<!Array<*>>} a
+ * @return {!Array<!Array<*>>}
+ */
+const rotate = a => a[0].map((e, i) => a.map(elAt(i)));
+
+/**
+ * Checks of all the elements in the array are the same.
+ * @param {!Array<*>} arr
+ * @return {boolean}
+ */
+const allElementsEqual = arr => arr.every(e => e === arr[0]);
+
+
+const commonPath = (input, sep = '/') => rotate(splitStrings(input, sep))
+    .filter(allElementsEqual).map(elAt(0)).join(sep);
+
+const cdpInput = [
+  '/home/user1/tmp/coverage/test',
+  '/home/user1/tmp/covert/operator',
+  '/home/user1/tmp/coven/members',
+];
+
+console.log(`Common path is: ${commonPath(cdpInput)}`);