Add changed property

.eslintignore

@@ -0,0 +1,3 @@
+node_modules
+coverage
+dist

.eslintrc

@@ -0,0 +1,20 @@
+{
+  "env": {
+    "browser": true,
+    "node": true,
+    "es6": true,
+    "jest": true
+  },
+  "extends": ["eslint:recommended", "plugin:react/recommended"],
+  "plugins": ["react", "react-hooks"],
+  "parser": "babel-eslint",
+  "rules": {
+    "react-hooks/rules-of-hooks": "error",
+    "react-hooks/exhaustive-deps": "warn"
+  },
+  "settings": {
+    "react": {
+      "version": "detect"
+    }
+  }
+}

.github/workflows/nodejs.yml

@@ -22,9 +22,10 @@ jobs:
       - name: Install latest npm
         run: npm install --global npm@latest
 
-      - name: npm install and test
+      - name: npm install, lint and test
         run: |
           npm install
+          npm run lint
           npm test -- --ci
         env:
           CI: true

.prettierignore

@@ -0,0 +1,5 @@
+node_modules
+coverage
+dist
+public
+tmp

CHANGELOG.md

@@ -2,6 +2,10 @@
 
 All notable changes to this project are documented in this file.
 
+## Unreleased
+
+- Added: `changed` callback argument.
+
 ## 0.1.3
 
 - Added: `payload` and `method` arguments.

README.md

@@ -13,7 +13,10 @@ If you need a simple way to load data quickly this is for you. It allows you to
 You can optionally specify a polling interval and manually trigger a refresh. It also gracefully cancels any open requests if you decide to change the URL and restarts timers if the polling interval changes.
 
 ```javascript
-const { data, loading, error, refresh } = useApi("https://some-api.com", 10000);
+const { data, loading, changed, error, refresh } = useApi(
+  "https://some-api.com",
+  10000
+);
 ```
 
 ## Installation
@@ -80,6 +83,7 @@ const PeopleSearch = () = {
 - `pollInterval` - How often to re-request updated data. Pass 0 to disable polling (the default behaviour).
 - `payload` - A data object to send in the request. If we are performing a GET request, it is appended into the querystring (e.g. `?keywords=hello`). If it is a POST request it is sent in the request body as JSON.
 - `method` - Set the request type, either `get` or `post`. (defaults to `get`)
+- `changed`: A function that is called if the data actually changed during the request. If this is specified, use-api does extra checking and compares old and new data. If data does not change, new data is not propagated and a redraw is saved. Please note, this may have performance repercussions if the data is large as it performs a deep comparison between new and old data to determine if they are equivalent.
 
 ### Output
 

index.js

@@ -1,22 +1,27 @@
-const { useEffect, useState } = require("react");
+const { useEffect, useState, useRef } = require("react");
 const axios = require("axios");
+const isEqual = require("lodash.isequal");
 
 const { CancelToken } = axios;
 
-const useApi = (apiEndpoint, pollInterval, payload, method = "get") => {
+const useApi = (
+  apiEndpoint,
+  pollInterval,
+  payload,
+  method = "get",
+  changed
+) => {
   const [data, setData] = useState({});
   const [error, setError] = useState(null);
   const [loading, setLoading] = useState(true);
   const [poll, setPoll] = useState(0);
+  const lastData = useRef(data);
 
-  // Function to force a refresh
-  const refresh = () => setPoll(poll + 1);
+  if (method.toLowerCase) method = method.toLowerCase();
 
   useEffect(() => {
     let timeout;
 
-    if (method.toLowerCase) method = method.toLowerCase();
-
     if (!["get", "post"].includes(method)) {
       setLoading(false);
       setError("Invalid request method type, must be either post or get.");
@@ -39,8 +44,18 @@ const useApi = (apiEndpoint, pollInterval, payload, method = "get") => {
       .then(response => {
         // Make sure there are no errors reported
         setError(null);
-        // Set the recieved data
-        setData(response.data);
+
+        // Only do change detection if change is defined.
+        if (changed) {
+          if (!isEqual(response.data, lastData.current)) {
+            // Set the received data ONLY IF its changed, redraw performance gain!
+            lastData.current = response.data;
+            setData(response.data);
+            changed(response.data);
+          }
+        } else {
+          setData(response.data);
+        }
       })
       .catch(thrown => {
         // Only error on genuine errors, not cancellations
@@ -51,17 +66,27 @@ const useApi = (apiEndpoint, pollInterval, payload, method = "get") => {
         setLoading(false);
 
         // Poll if specified to do so
-        if (pollInterval) timeout = setTimeout(refresh, pollInterval);
+        if (pollInterval)
+          timeout = setTimeout(() => setPoll(poll + 1), pollInterval);
       });
 
     // Cleanup, clear a timeout and cancel the request.
     return () => {
       if (timeout) clearTimeout(timeout);
       source.cancel();
     };
-  }, [poll, apiEndpoint, pollInterval]);
+  }, [
+    poll,
+    setPoll,
+    apiEndpoint,
+    pollInterval,
+    payload,
+    method,
+    lastData,
+    changed
+  ]);
 
-  return { data, loading, error, refresh };
+  return { data, loading, changed, error, refresh: () => setPoll(poll + 1) };
 };
 
 module.exports = useApi;