Add scaffolding + Two props update check

.editorconfig

@@ -0,0 +1,8 @@
+root = true
+
+[*]
+indent_style = space
+indent_size = 2
+charset = utf-8
+trim_trailing_whitespace = false
+insert_final_newline = false

src/App.css

@@ -2,31 +2,13 @@
   text-align: center;
 }
 
-.App-logo {
+.controls {
-  animation: App-logo-spin infinite 20s linear;
+  background-color: white;
-  height: 40vmin;
+  position: sticky;
+  top: 0;
 }
 
-.App-header {
+button {
-  background-color: #282c34;
+  font-size: 2em;
-  min-height: 100vh;
+  margin: 1em 1em;
-  display: flex;
-  flex-direction: column;
-  align-items: center;
-  justify-content: center;
-  font-size: calc(10px + 2vmin);
-  color: white;
-}
-
-.App-link {
-  color: #61dafb;
-}
-
-@keyframes App-logo-spin {
-  from {
-    transform: rotate(0deg);
-  }
-  to {
-    transform: rotate(360deg);
-  }
 }

src/App.js

@@ -1,25 +1,67 @@
 import React, { Component } from 'react';
-import logo from './logo.svg';
+import SectionManager from './components/SectionManager';
+
 import './App.css';
 
 class App extends Component {
+  constructor(props) {
+    super(props);
+
+    this.state = {
+      scroll: {
+        sectionName: 'C',
+      },
+      post: {
+        postNumber: 1,
+      },
+    };
+  }
+
+  scrollToSectionA = () => {
+    this.setState({
+      scroll: {
+        sectionName: 'A',
+      }
+    })
+  }
+
+  scrollToSectionC = () => {
+    this.setState({
+      scroll: {
+        sectionName: 'C',
+      }
+    })
+  }
+
+  changeText = () => {
+    this.setState(
+      (oldState) => ({
+        post: {
+          postNumber: oldState.post.postNumber + 1,
+        }
+      })
+    )
+  }
+
+  scrollToTopAndChangeText = () => {
+    this.scrollToSectionA();
+    this.changeText();
+  }
+
   render() {
     return (
       <div className="App">
-        <header className="App-header">
+        <div className="controls" >
-          <img src={logo} className="App-logo" alt="logo" />
+          <button onClick={this.scrollToSectionA}>Scroll to A</button>
-          <p>
+          <button onClick={this.scrollToSectionC}>Scroll to C</button>
-            Edit <code>src/App.js</code> and save to reload.
+          <button onClick={this.changeText}>Fetch new text content</button>
-          </p>
+          <button onClick={this.scrollToTopAndChangeText}>Scroll to A and Fetch text</button>
-          <a
+        </div>
-            className="App-link"
+        <SectionManager
-            href="https://reactjs.org"
+          {
-            target="_blank"
+          ...this.state
-            rel="noopener noreferrer"
+          }
-          >
+        />
-            Learn React
-          </a>
-        </header>
       </div>
     );
   }

src/components/SectionManager/index.js

@@ -0,0 +1,83 @@
+import React, { Component, createRef } from 'react';
+import SectionA from '../../sections/SectionA';
+import SectionB from '../../sections/SectionB';
+import SectionC from '../../sections/SectionC';
+
+export default class SectionManager extends Component {
+  static placeHolderURL = 'https://jsonplaceholder.typicode.com/posts';
+
+  constructor(props) {
+    super(props);
+
+    this.state = {
+      sectionBody: undefined,
+    };
+
+    this.sectionRefs = {
+      'A': createRef(),
+      'B': createRef(),
+      'C': createRef(),
+    }
+  }
+
+  componentWillReceiveProps(nextProps) {
+    const { scroll: scrollProps, post: postProps } = nextProps;
+    const { scroll: oldScrollProps, post: oldPostProps } = this.props;
+
+    if (scrollProps.sectionName !== oldScrollProps.sectionName) {
+      this.scrollToSection(scrollProps.sectionName)
+    }
+
+    if (postProps.postNumber !== oldPostProps.postNumber) {
+      this.updateSectionBody(postProps.postNumber);
+    }
+  }
+
+  componentDidMount() {
+    this.updateSectionBody(this.props.post.postNumber);
+
+    setTimeout(() => { this.scrollToSection(this.props.scroll.sectionName); }, 500);
+
+  }
+
+  updateSectionBody(postNumber) {
+    this.setState({
+      sectionBody: undefined,
+    })
+
+    fetch(`${SectionManager.placeHolderURL}/${postNumber}`)
+      .then((responseString) => {
+        return responseString.json();
+      })
+      .then((responseObject) => {
+        this.setState({
+          sectionBody: responseObject.body,
+        });
+      });
+
+  }
+
+  scrollToSection(sectionName) {
+    const sectionRef = this.sectionRefs[sectionName];
+    console.log(sectionRef.current, sectionRef.current !== null);
+
+    if (
+      (sectionRef !== undefined) &&
+      (sectionRef.current !== null)
+    ) {
+      sectionRef.current.scrollIntoView({
+        behavior: 'smooth'
+      });
+    }
+  }
+
+  render() {
+    return (
+      <div>
+        <SectionA ref={this.sectionRefs.A} body={this.state.sectionBody} />
+        <SectionB ref={this.sectionRefs.B} body={this.state.sectionBody} />
+        <SectionC ref={this.sectionRefs.C} body={this.state.sectionBody} />
+      </div>
+    );
+  }
+}

src/logo.svg

@@ -1,7 +0,0 @@
-<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 841.9 595.3">
-    <g fill="#61DAFB">
-        <path d="M666.3 296.5c0-32.5-40.7-63.3-103.1-82.4 14.4-63.6 8-114.2-20.2-130.4-6.5-3.8-14.1-5.6-22.4-5.6v22.3c4.6 0 8.3.9 11.4 2.6 13.6 7.8 19.5 37.5 14.9 75.7-1.1 9.4-2.9 19.3-5.1 29.4-19.6-4.8-41-8.5-63.5-10.9-13.5-18.5-27.5-35.3-41.6-50 32.6-30.3 63.2-46.9 84-46.9V78c-27.5 0-63.5 19.6-99.9 53.6-36.4-33.8-72.4-53.2-99.9-53.2v22.3c20.7 0 51.4 16.5 84 46.6-14 14.7-28 31.4-41.3 49.9-22.6 2.4-44 6.1-63.6 11-2.3-10-4-19.7-5.2-29-4.7-38.2 1.1-67.9 14.6-75.8 3-1.8 6.9-2.6 11.5-2.6V78.5c-8.4 0-16 1.8-22.6 5.6-28.1 16.2-34.4 66.7-19.9 130.1-62.2 19.2-102.7 49.9-102.7 82.3 0 32.5 40.7 63.3 103.1 82.4-14.4 63.6-8 114.2 20.2 130.4 6.5 3.8 14.1 5.6 22.5 5.6 27.5 0 63.5-19.6 99.9-53.6 36.4 33.8 72.4 53.2 99.9 53.2 8.4 0 16-1.8 22.6-5.6 28.1-16.2 34.4-66.7 19.9-130.1 62-19.1 102.5-49.9 102.5-82.3zm-130.2-66.7c-3.7 12.9-8.3 26.2-13.5 39.5-4.1-8-8.4-16-13.1-24-4.6-8-9.5-15.8-14.4-23.4 14.2 2.1 27.9 4.7 41 7.9zm-45.8 106.5c-7.8 13.5-15.8 26.3-24.1 38.2-14.9 1.3-30 2-45.2 2-15.1 0-30.2-.7-45-1.9-8.3-11.9-16.4-24.6-24.2-38-7.6-13.1-14.5-26.4-20.8-39.8 6.2-13.4 13.2-26.8 20.7-39.9 7.8-13.5 15.8-26.3 24.1-38.2 14.9-1.3 30-2 45.2-2 15.1 0 30.2.7 45 1.9 8.3 11.9 16.4 24.6 24.2 38 7.6 13.1 14.5 26.4 20.8 39.8-6.3 13.4-13.2 26.8-20.7 39.9zm32.3-13c5.4 13.4 10 26.8 13.8 39.8-13.1 3.2-26.9 5.9-41.2 8 4.9-7.7 9.8-15.6 14.4-23.7 4.6-8 8.9-16.1 13-24.1zM421.2 430c-9.3-9.6-18.6-20.3-27.8-32 9 .4 18.2.7 27.5.7 9.4 0 18.7-.2 27.8-.7-9 11.7-18.3 22.4-27.5 32zm-74.4-58.9c-14.2-2.1-27.9-4.7-41-7.9 3.7-12.9 8.3-26.2 13.5-39.5 4.1 8 8.4 16 13.1 24 4.7 8 9.5 15.8 14.4 23.4zM420.7 163c9.3 9.6 18.6 20.3 27.8 32-9-.4-18.2-.7-27.5-.7-9.4 0-18.7.2-27.8.7 9-11.7 18.3-22.4 27.5-32zm-74 58.9c-4.9 7.7-9.8 15.6-14.4 23.7-4.6 8-8.9 16-13 24-5.4-13.4-10-26.8-13.8-39.8 13.1-3.1 26.9-5.8 41.2-7.9zm-90.5 125.2c-35.4-15.1-58.3-34.9-58.3-50.6 0-15.7 22.9-35.6 58.3-50.6 8.6-3.7 18-7 27.7-10.1 5.7 19.6 13.2 40 22.5 60.9-9.2 20.8-16.6 41.1-22.2 60.6-9.9-3.1-19.3-6.5-28-10.2zM310 490c-13.6-7.8-19.5-37.5-14.9-75.7 1.1-9.4 2.9-19.3 5.1-29.4 19.6 4.8 41 8.5 63.5 10.9 13.5 18.5 27.5 35.3 41.6 50-32.6 30.3-63.2 46.9-84 46.9-4.5-.1-8.3-1-11.3-2.7zm237.2-76.2c4.7 38.2-1.1 67.9-14.6 75.8-3 1.8-6.9 2.6-11.5 2.6-20.7 0-51.4-16.5-84-46.6 14-14.7 28-31.4 41.3-49.9 22.6-2.4 44-6.1 63.6-11 2.3 10.1 4.1 19.8 5.2 29.1zm38.5-66.7c-8.6 3.7-18 7-27.7 10.1-5.7-19.6-13.2-40-22.5-60.9 9.2-20.8 16.6-41.1 22.2-60.6 9.9 3.1 19.3 6.5 28.1 10.2 35.4 15.1 58.3 34.9 58.3 50.6-.1 15.7-23 35.6-58.4 50.6zM320.8 78.4z"/>
-        <circle cx="420.9" cy="296.5" r="45.7"/>
-        <path d="M520.5 78.1z"/>
-    </g>
-</svg>

src/sections/SectionA/index.js

@@ -0,0 +1,23 @@
+import React, { Component } from 'react';
+
+import '../section.css';
+
+class SectionA extends Component {
+  render() {
+    return (
+      <div className="section" ref={this.props.forwardedRef}>
+        <div className="section-text">
+          This is section A
+        <br />
+          {
+            this.props.body
+          }
+        </div>
+      </div>
+    )
+  }
+};
+
+export default React.forwardRef((props, ref) => {
+  return <SectionA {...props} forwardedRef={ref} />;
+});

src/sections/SectionB/index.js

@@ -0,0 +1,23 @@
+import React, { Component } from 'react';
+
+import '../section.css';
+
+class SectionB extends Component {
+  render() {
+    return (
+      <div className="section" ref={this.props.forwardedRef}>
+        <div className="section-text">
+          This is section B
+        <br />
+          {
+            this.props.body
+          }
+        </div>
+      </div>
+    )
+  }
+};
+
+export default React.forwardRef((props, ref) => {
+  return <SectionB {...props} forwardedRef={ref} />;
+});

src/sections/SectionC/index.js

@@ -0,0 +1,23 @@
+import React, { Component } from 'react';
+
+import '../section.css';
+
+class SectionC extends Component {
+  render() {
+    return (
+      <div className="section" ref={this.props.forwardedRef}>
+        <div className="section-text">
+          This is section C
+        <br />
+          {
+            this.props.body
+          }
+        </div>
+      </div>
+    )
+  }
+};
+
+export default React.forwardRef((props, ref) => {
+  return <SectionC {...props} forwardedRef={ref} />;
+});

src/sections/section.css

@@ -0,0 +1,23 @@
+.section {
+  width: 100%;
+  min-height: 50vh;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  font-size: 2em;
+}
+
+.section:nth-child(1) {
+  background-color: darkblue;
+  color: azure;
+}
+
+.section:nth-child(2) {
+  background-color: lightblue;
+  color: blueviolet;
+}
+
+.section:nth-child(3) {
+  background-color: darkblue;
+  color: azure;
+}