chore(Javascript): add fibonacci series (#752)

* Add fibonacci series for javascript

* Added doc in js readme for fibonacci series

* Add user-friendly description of algorithm in comments

* fix change fibs to series

* fix output spelling

* add time complexity

algorithms/JavaScript/README.md

@@ -1,18 +1,22 @@
 # JavaScript
 
 ## Arrays
+
 - [Counting Inversions](src/arrays/counting-inversions.js)
 
 ## Linked Lists
+
 - [Singly](src/linked-lists/singly.js)
 - [Doubly](src/linked-lists/doubly.js)
 
 ## Searching
+
 - [Binary Search Recursive](src/searching/binary-search-recursive.js)
 - [Binary Search](src/searching/binary-search.js)
 - [Linear Search](src/searching/linear-search.js)
 
 ## Sorting
+
 - [Bubble Sort](src/sorting/bubble-sort.js)
 - [Insertion Sort](src/sorting/insertion-sort.js)
 - [Merge Sort](src/sorting/merge-sort.js)
@@ -20,12 +24,19 @@
 - [Selection Sort](src/sorting/selection-sort.js)
 
 ## Strings
+
 - [Palindrome](src/strings/palindrome.js)
 - [Sequence](src/strings/sequence.js)
 
 ## Stacks
+
 - [Stacks](src/stacks/stack.js)
 - [Two Stack](src/stacks/two-stack.js)
 
 ## Queues
+
 - [Queue](src/queues/queue.js)
+
+## Maths
+
+- [Fibonacci Series](src/maths/fibonacci-series.js)

algorithms/JavaScript/src/index.js

@@ -4,6 +4,9 @@ require('./arrays/counting-inversions');
 // Linked Lists
 require('./linked-lists/singly');
 
+// Maths
+require('./maths/fibonacci-series');
+
 // Searching
 require('./searching/binary-search-recursive');
 require('./searching/binary-search');
@@ -22,7 +25,7 @@ require('./strings/sequence');
 
 // Stack
 require('./stacks/stack');
-require('./stacks/two-stack')
+require('./stacks/two-stack');
 
 // Queue
 require('./queues/queue');

algorithms/JavaScript/src/maths/fibonacci-series.js

@@ -0,0 +1,24 @@
+// algorithm to generate first n numbers of fibonacci series
+// Time complexity: O(n)
+
+function fibonacci(n) {
+  // Initialize array 'series'
+  // with the first two numbers of the fibonacci series [0, 1]
+  const series = [0, 1];
+  for (let i = 3; i <= n; i++) {
+    // starting from the third number, and stopping at number n
+    const num1 = series[series.length - 1];
+    // num1 is the last number of the series
+    const num2 = series[series.length - 2];
+    // num2 is the second-to-last number of the series
+    const next = num1 + num2;
+    // next number is the sum of the last two
+    series.push(next);
+    // add number to list
+  }
+  // return list
+  return series;
+}
+
+console.log(fibonacci(10));
+// output: [0, 1,  1,  2,  3, 5, 8, 13, 21, 34]