Convert App to functional component

src/App.tsx

@@ -1,4 +1,4 @@
-import React, {Component} from 'react';
+import React, {useState} from 'react';
 
 import './App.scss';
 import {declineSaimiar} from './saimiar_morphology';
@@ -145,86 +145,80 @@ const Results = (props: ResultsProps) => {
     );
 };
 
-interface App {
-    [x: string]: any;
-}
+const App = (_props) => {
+    const [searchResults, setSearchResults] = useState(null);
+    const [conlang, setConlang] = useState(Conlang.Saimiar);
+    const [direction, setDirection] = useState(null);
+    const [searchTerm, setSearchTerm] = useState(null);
 
-class App extends Component {
-    constructor(props) {
-        super(props);
-        this.input = React.createRef();
-        this.handleLangChange = this.handleLangChange.bind(this);
+    const [searchBoxInput, setSearchBoxInput] = useState('');
 
-        this.searchEng = this.searchEng.bind(this);
-        this.searchSaimiar = this.searchSaimiar.bind(this);
-        this.searchJuteyuji = this.searchJuteyuji.bind(this);
-        this.searchConlang = this.searchConlang.bind(this);
-
-        this.state = {
-            searchResults: null,
-            conlang: Conlang.Saimiar,
-            direction: null,
-            searchTerm: null,
-        };
-    }
-
-    searchConlang(_evt) {
-        const searchTerm = this.input.current.value;
-        const {conlang} = this.state;
+    const searchConlang = (_evt) => {
+        const searchTerm = searchBoxInput;
         if (conlang === Conlang.Saimiar) {
-            this.searchSaimiar(searchTerm);
+            searchSaimiar(searchTerm);
         } else if (conlang === Conlang.Juteyuji) {
-            this.searchJuteyuji(searchTerm);
+            searchJuteyuji(searchTerm);
         } else {
             console.error(`Conlang ${conlang} not supported`);
         }
-    }
+    };
 
-    searchSaimiar(searchTerm: string) {
+    const searchSaimiar = (searchTerm: string) => {
         const request = `saimiar?sai=like.*${searchTerm}*`;
         if (searchTerm === '') {
-            this.setState({searchResults: null, searchTerm: null, direction: null});
+            setSearchResults(null);
+            setSearchTerm(null);
+            setDirection(null);
         } else {
             makeRequest(request, (json) => {
-                this.setState({searchResults: json, searchTerm, direction: SearchDirection.ToEnglish});
+                setSearchResults(json);
+                setSearchTerm(searchTerm);
+                setDirection(SearchDirection.ToEnglish);
             });
         }
-    }
+    };
 
-    searchJuteyuji(searchTerm: string) {
+    const searchJuteyuji = (searchTerm: string) => {
         const request = `juteyuji?jut=like.*${searchTerm}*`;
         if (searchTerm === '') {
-            this.setState({searchResults: null, searchTerm: null, direction: null});
+            setSearchResults(null);
+            setSearchTerm(null);
+            setDirection(null);
         } else {
             makeRequest(request, (json) => {
-                this.setState({searchResults: json, searchTerm, direction: SearchDirection.ToEnglish});
+                setSearchResults(json);
+                setSearchTerm(searchTerm);
+                setDirection(SearchDirection.ToEnglish);
             });
         }
-    }
+    };
 
-    searchEng(_evt) {
-        const searchTerm = this.input.current.value;
-        const {conlang} = this.state;
+    const searchEng = (_evt) => {
+        const searchTerm = searchBoxInput;
         const request = `${conlang}?eng=like.*${searchTerm}*`;
         if (searchTerm === '') {
-            this.setState({searchResults: null, searchTerm: null});
+            setSearchResults(null);
+            setSearchTerm(null);
         } else {
             makeRequest(request, (json) => {
-                this.setState({searchResults: json, searchTerm, direction: SearchDirection.ToConlang});
+                setSearchResults(json);
+                setSearchTerm(searchTerm);
+                setDirection(SearchDirection.ToConlang);
             });
         }
-    }
+    };
 
-    handleLangChange(evt) {
+    const handleLangChange = (evt) => {
         const conlang: Conlang = evt.target.value as Conlang;
         console.log('Conlang in handlelangchange', conlang);
-        this.setState({conlang, searchResults: null});
-    }
+        setConlang(conlang);
+        setSearchResults(null);
+    };
 
-    render() {
     const conlangs = [Conlang.Saimiar, Conlang.Elesu, Conlang.Tukvaysi, Conlang.Juteyuji];
     const langSelectDropdown = (
-            <select ref={ this.langSelection } onChange={ this.handleLangChange } defaultValue={Conlang.Saimiar}>
+        <select value={conlang} onChange={ handleLangChange }>
             {conlangs.map((conlang) => <option value={conlang} key={conlang}>{renderConlang(conlang)}</option>)}
         </select>
     );
@@ -235,23 +229,24 @@ class App extends Component {
                 <div className="search">
                     <h1>Kucinako</h1>
                     <div className="textInput">
-                            <input className="textInput" type="text" ref={ this.input } />
+                        <input className="textInput" type="text" value={ searchBoxInput } onChange={ (evt) => {
+                            setSearchBoxInput(evt.target.value);
+                        } } />
                     </div>
                     <br/>
                     { langSelectDropdown }
-                        <button onClick={ this.searchConlang } className="searchButton">{renderConlang(this.state.conlang)}</button>
-                        <button onClick={ this.searchEng } className="searchButton">English</button>
+                    <button onClick={ searchConlang } className="searchButton">{renderConlang(conlang)}</button>
+                    <button onClick={ searchEng } className="searchButton">English</button>
                 </div>
                 <Results
-                        searchResults={ this.state.searchResults }
-                        searchTerm= { this.state.searchTerm }
-                        conlang={ this.state.conlang }
-                        direction={ this.state.direction }
+                    searchResults={ searchResults }
+                    searchTerm= { searchTerm }
+                    conlang={ conlang }
+                    direction={ direction }
                 />
             </div>
         </main>
     );
-    }
-}
+};
 
 export default App;