Done

index.js

@@ -0,0 +1,25 @@
+function updateObjectWithKeyAndValue(obj, key, val) {
+  // NON-DESTRUCTIVE!
+  let resultObj = {};
+  resultObj = Object.assign(resultObj, obj);
+  resultObj[key] = val;
+  return resultObj;
+}
+
+function destructivelyUpdateObjectWithKeyAndValue(obj, key, val) {
+  obj[key] = val;
+  return obj;
+}
+
+function deleteFromObjectByKey(obj, key) {
+  // NON-DESTRUCTIVE!
+  let resultObj = {};
+  resultObj = Object.assign(resultObj, obj);
+  delete resultObj[key];
+  return resultObj;
+}
+
+function destructivelyDeleteFromObjectByKey(obj, key) {
+  delete obj[key];
+  return obj;
+}