add FibonacciNumber.js

Author: Vijay-K-2003

fibonacci_number/FibonacciNumber.js

@@ -0,0 +1,31 @@
+function fibonacci(p) {
+    if(p === 1 || p === 2) {
+        return p-1; // base case
+    } else {
+
+        let a = 0;
+        let b = 1;
+        // 0 1 1 2 3 5 8 ...
+        let fib = 0;
+        for(var i = 2 ; i < p ; i = i + 1) {
+            fib = a + b;
+            a = b;
+            b = fib;
+        }
+
+        return fib;
+    }
+}
+
+
+const readline = require('readline').createInterface({
+    input: process.stdin,
+    output: process.stdout
+  });
+  
+readline.question("Enter value of n ", n => {
+    console.log(fibonacci(n));
+    readline.close()
+  });
+  
+