created & manipulated employee details according to test files

index.js

@@ -1 +1,34 @@
-// Write your solution in this file!
+const employee = {
+  name: "John Doe",
+  streetAddress: "123 Main St",
+};
+
+function updateEmployeeWithKeyAndValue(employee, key, value) {
+  return {
+    ...employee,
+    [key]: value,
+  };
+}
+
+function destructivelyUpdateEmployeeWithKeyAndValue(employee, key, value) {
+  employee[key] = value;
+  return employee;
+}
+
+function deleteFromEmployeeByKey(employee, key) {
+  const newEmployee = { ...employee };
+  delete newEmployee[key];
+  return newEmployee;
+}
+
+function destructivelyDeleteFromEmployeeByKey(employee, key) {
+  delete employee[key];
+  return employee;
+}
+
+module.exports = {
+  updateEmployeeWithKeyAndValue,
+  destructivelyUpdateEmployeeWithKeyAndValue,
+  deleteFromEmployeeByKey,
+  destructivelyDeleteFromEmployeeByKey,
+};