Copying elements to avoid mutating data structures

Author: brenda-jimenez

lib/state-api/lib/index.js

@@ -9,6 +9,31 @@ class StateApi{
             timestamp: new Date()};
         this.subscriptions ={};
         this.lastSubscriptionId=0;
+
+        //Simulating adding an article every minute
+        setTimeout(() => {
+            const fakeArticle = {
+                ...rawData.articles[0],
+                id: 'fakeArticleId',
+            };
+            //This line mutates the state and that wont be recognized by the PureComponent
+            // this.data.articles[fakeArticle.id] = fakeArticle;
+
+            //Hence instead of mutating the state we will copy
+            //We are copying the current state and modifying that copy of the current state
+            //So for the previous object and current object are different
+            //Copying current data
+            //Change the articles object
+            //add new article
+            this.data = {
+                ...this.data,
+                articles: {
+                    ...this.data.articles,
+                    [fakeArticle.id]: fakeArticle,
+                },
+            };
+            this.notifySubscribers();
+        }, 1000);
     }