initial commit

.gitignore

@@ -21,3 +21,6 @@
 npm-debug.log*
 yarn-debug.log*
 yarn-error.log*
+
+/.idea
+/ignored

package.json

@@ -3,9 +3,17 @@
   "version": "0.1.0",
   "private": true,
   "dependencies": {
-    "react": "^16.6.0",
-    "react-dom": "^16.6.0",
-    "react-scripts": "2.1.1"
+    "foobar-ipsum": "^1.0.3",
+    "immer": "^1.7.4",
+    "node-sass": "^4.9.4",
+    "normalize.css": "^8.0.0",
+    "react": "16.7.0-alpha.0",
+    "react-dom": "16.7.0-alpha.0",
+    "react-router-dom": "^4.3.1",
+    "react-scripts": "2.1.1",
+    "scroll-into-view-if-needed": "^2.2.20",
+    "simple-react-router": "^0.0.17",
+    "yup": "^0.26.6"
   },
   "scripts": {
     "start": "react-scripts start",
@@ -14,12 +22,25 @@
     "eject": "react-scripts eject"
   },
   "eslintConfig": {
-    "extends": "react-app"
+    "extends": "react-app",
+    "plugins": [
+      "react-hooks"
+    ],
+    "rules": {
+      "react-hooks/rules-of-hooks": "error"
+    }
   },
   "browserslist": [
     ">0.2%",
     "not dead",
     "not ie <= 11",
     "not op_mini all"
-  ]
+  ],
+  "devDependencies": {
+    "eslint-plugin-react-hooks": "^0.0.0"
+  },
+  "now": {
+    "alias": "awesome-hooks.now-sh",
+    "name": "awesome-hooks"
+  }
 }

src/App.js

@@ -1,28 +1,55 @@
-import React, { Component } from 'react';
-import logo from './logo.svg';
-import './App.css';
+import React from 'react';
+import { BrowserRouter as Router, Route, Link } from 'react-router-dom';
 
-class App extends Component {
-  render() {
-    return (
-      <div className="App">
-        <header className="App-header">
-          <img src={logo} className="App-logo" alt="logo" />
-          <p>
-            Edit <code>src/App.js</code> and save to reload.
-          </p>
-          <a
-            className="App-link"
-            href="https://reactjs.org"
-            target="_blank"
-            rel="noopener noreferrer"
-          >
-            Learn React
-          </a>
-        </header>
+import AccordionScreen from './components/accordion';
+import Screen from './components/form-library';
+import WindowWidthScreen from './components/window-width';
+import TodoList from "./components/todolist";
+
+function App() {
+  return (
+    <Router>
+      <div className="main">
+        <nav className="sidebar">
+          <div className="item">
+            <Link className="link" to="/accordion">
+              Accordion
+            </Link>
+            <span>
+              Panels scroll into view if not fully visible when toggled.
+              Using <pre>useImperativeMethods</pre> and <pre>useRef</pre>.
+            </span>
+          </div>
+          <div className="item">
+            <Link className="link" to="/form-library">
+              Extremely basic form validation library
+            </Link>
+            <span>Pass state deeper using context, then read it using <pre>useContext</pre>. Heavily inspired by <pre>formik</pre>.</span>
+          </div>
+          <div className="item">
+            <Link className="link" to="/window-width">
+              Window width
+            </Link>
+            <span>Multiple <pre>useEffects</pre> are allowed.</span>
+          </div>
+          <div className="item">
+            <Link className="link" to="/todo-list">
+              Todo-list
+            </Link>
+            <span>Look mum, <pre>useReducer</pre> is almost Redux!</span>
+          </div>
+        </nav>
+
+        <div className="content">
+          <Route path="/" exact component={() => <div>use navigation on the left</div>}/>
+          <Route path="/accordion" component={AccordionScreen}/>
+          <Route path="/form-library" component={Screen}/>
+          <Route path="/window-width" component={WindowWidthScreen}/>
+          <Route path="/todo-list" component={TodoList}/>
+        </div>
       </div>
-    );
-  }
+    </Router>
+  )
 }
 
-export default App;
+export default App;

src/components/accordion/Accordion.js

@@ -0,0 +1,72 @@
+import React, { useRef, createRef, useImperativeMethods, useState, useEffect } from 'react';
+import scrollIntoView from 'scroll-into-view-if-needed';
+import FoobarIpsum from 'foobar-ipsum';
+
+function useAccordion(panelsCount) {
+  const [currentIndex, setCurrentIndex] = useState();
+  const [refs, setRefs] = useState();
+
+  // This part is smelly
+  // https://github.com/facebook/react/issues/14072
+  // TODO rewrite
+  useEffect(() => {
+    let refs = {};
+    for (let i = 0; i <= panelsCount; i++) {
+      refs[i] = createRef();
+    }
+    setRefs(refs);
+  }, []);
+
+  useEffect(() => {
+    // Scroll current accordion panel into view
+    if (currentIndex !== undefined) {
+      refs[currentIndex].current.scrollIntoView();
+    }
+  }, [currentIndex]);
+
+  function setCurrent(newIndex) {
+    setCurrentIndex(currentIndex === newIndex ? undefined : newIndex);
+  }
+
+  return [currentIndex, setCurrent, refs];
+}
+
+const AccordionPanel = React.forwardRef((props, ref) => {
+  const containerRef = useRef();
+  const textRef = useRef();
+
+  useImperativeMethods(ref, () => ({
+    scrollIntoView: () => {
+      scrollIntoView(containerRef.current, { block: 'nearest', scrollMode: 'if-needed' });
+    }
+  }));
+
+  return <div onClick={props.onClick} ref={containerRef}>
+    <div className="accordion-label">{props.label}</div>
+    {props.isOpen &&
+    <div>{generateRandomText()}</div>}
+  </div>;
+});
+
+function Accordion(props) {
+  return <div>{props.children}</div>;
+}
+
+function generateRandomNumber(max) {
+  return Math.floor(Math.random() * Math.floor(max));
+}
+
+function generateRandomText() {
+  return new FoobarIpsum({
+    size: {
+      sentence: generateRandomNumber(100),
+      paragraph: generateRandomNumber(10)
+    }
+  }).paragraph();
+}
+
+export {
+  useAccordion,
+  Accordion,
+  AccordionPanel
+};

src/components/accordion/index.js

@@ -0,0 +1,23 @@
+import React from 'react';
+
+import { Accordion, AccordionPanel, useAccordion } from './Accordion';
+
+function AccordionScreen() {
+  const panels = [...Array(100).keys()].map(e => `Panel number ${e}`);
+
+  const [currentIndex, setCurrent, refs] = useAccordion(panels.length);
+
+  return <Accordion>
+    {panels.map((panel, index) => (
+      <AccordionPanel
+        ref={refs && refs[index]}
+        key={index}
+        label={panel}
+        isOpen={currentIndex === index}
+        onClick={() => setCurrent(index)}
+      />
+    ))}
+  </Accordion>;
+}
+
+export default AccordionScreen;

src/components/form-library/FormLibrary.js

@@ -0,0 +1,61 @@
+import React, { useState, useEffect, createContext } from "react";
+
+const FormContext = createContext(null);
+
+function MyFormLibrary({ children, initialValues, onValuesChanged, onSubmit, validate }) {
+  const [values, updateValues] = useState(initialValues);
+  const [errors, updateErrors] = useState({});
+
+  useEffect(() => {
+    if (typeof onValuesChanged === 'function') {
+      onValuesChanged(values);
+    }
+  }, [values]);
+
+  function handleChange(e) {
+    updateValues({
+      ...values,
+      [e.target.name]: e.target.value
+    });
+    updateErrors({
+      ...errors,
+      [e.target.name]: undefined
+    });
+  }
+
+  async function submitForm() {
+    try {
+      validate && validate(values);
+      await onSubmit(values);
+    } catch (e) {
+      updateErrors(convertErrors(e));
+    }
+  }
+
+  function handleSubmit(e) {
+    e.preventDefault();
+    submitForm();
+  }
+
+  const ctx = {
+    values,
+    errors,
+    handleChange,
+    handleSubmit
+  };
+
+  return <FormContext.Provider value={ctx}>
+    {children}
+  </FormContext.Provider>;
+}
+
+function convertErrors(yupError) {
+  return yupError.inner
+    .reduce((acc, cur) => {
+      acc[cur.path] = cur.message;
+      return acc;
+    }, {});
+}
+
+export default MyFormLibrary;
+export { FormContext };