Added script.js file

Author: Yuvrajchandra

script.js

@@ -0,0 +1,17 @@
+// This function clear all the values
+function clearScreen() {
+    document.getElementById("result").value = "";
+}
+
+
+// This function display values
+function display(value) {
+    document.getElementById("result").value += value;
+}
+
+// This function evaluates the expression and return result
+function calculate() {
+    var p = document.getElementById("result").value;
+    var q = eval(p);
+    document.getElementById("result").value = q;
+}