Complete fibonacci challenge

Author: ChiselD

fibonacci/fibonacci.js

@@ -1,5 +1,12 @@
-const fibonacci = function() {
-
+const fibonacci = function(n) {
+	if (n < 0) {return "OOPS";}
+	let x = 0, y = 1, z = 0;
+	for (let i = 0; i < n; i++) {
+		z = x + y; // x = 0, y = 1, z = 1
+		x = y;
+		y = z;
+	}
+	return x;
 }
 
 module.exports = fibonacci

fibonacci/fibonacci.spec.js

@@ -4,28 +4,28 @@ describe('fibonacci', function() {
   it('works', function() {
     expect(fibonacci(4)).toEqual(3);
   });
-  xit('works', function() {
+  it('works', function() {
     expect(fibonacci(6)).toEqual(8);
   });
-  xit('works', function() {
+  it('works', function() {
     expect(fibonacci(10)).toEqual(55);
   });
-  xit('works', function() {
+  it('works', function() {
     expect(fibonacci(15)).toEqual(610);
   });
-  xit('works', function() {
+  it('works', function() {
     expect(fibonacci(25)).toEqual(75025);
   });
-  xit('doesn\'t accept negatives', function() {
+  it('doesn\'t accept negatives', function() {
     expect(fibonacci(-25)).toEqual("OOPS");
   });
-  xit('DOES accept strings', function() {
+  it('DOES accept strings', function() {
     expect(fibonacci("1")).toEqual(1);
   });
-  xit('DOES accept strings', function() {
+  it('DOES accept strings', function() {
     expect(fibonacci("2")).toEqual(1);
   });
-  xit('DOES accept strings', function() {
+  it('DOES accept strings', function() {
     expect(fibonacci("8")).toEqual(21);
   });
 });