Add JSDoc documentation to App.js

frontend/src/App.js

@@ -1,18 +1,58 @@
+/**
+ * @fileoverview Superhero Comparison Application
+ * 
+ * This React application provides a user interface for viewing, selecting, and comparing
+ * superheroes based on their power statistics. Users can view a table of superheroes,
+ * select up to two heroes, and compare their stats head-to-head to determine a winner.
+ * 
+ * The application has two main views:
+ * - Table View: Displays all superheroes in a table with their statistics
+ * - Comparison View: Shows a side-by-side comparison of two selected heroes
+ * 
+ * @author Copilot
+ * @requires react
+ * @requires ./App.css
+ */
+
 import React, { useEffect, useState } from 'react';
 import './App.css';
 
+/**
+ * Main App component that manages the superhero comparison application.
+ * 
+ * This component handles the entire application state including fetching superhero data,
+ * managing hero selections, switching between views, and rendering the appropriate UI.
+ * 
+ * @component
+ * @returns {JSX.Element} The rendered App component
+ */
 function App() {
   const [superheroes, setSuperheroes] = useState([]);
   const [selectedHeroes, setSelectedHeroes] = useState([]);
   const [currentView, setCurrentView] = useState('table'); // 'table' or 'comparison'
 
+  /**
+   * Fetches the list of superheroes from the API on component mount.
+   * Uses the useEffect hook to trigger the fetch operation once when the component is first rendered.
+   */
   useEffect(() => {
     fetch('/api/superheroes')
       .then((response) => response.json())
       .then((data) => setSuperheroes(data))
       .catch((error) => console.error('Error fetching superheroes:', error));
   }, []);
 
+  /**
+   * Handles the selection/deselection of a superhero.
+   * 
+   * This function manages the selection logic with the following rules:
+   * - If a hero is already selected, clicking them will deselect them
+   * - If fewer than 2 heroes are selected, the clicked hero is added to the selection
+   * - If 2 heroes are already selected, the oldest selection is replaced with the new one
+   * 
+   * @param {Object} hero - The superhero object to select or deselect
+   * @param {number} hero.id - The unique identifier of the superhero
+   */
   const handleHeroSelection = (hero) => {
     setSelectedHeroes(prev => {
       if (prev.find(h => h.id === hero.id)) {
@@ -22,32 +62,66 @@ function App() {
         // Add if less than 2 selected
         return [...prev, hero];
       } else {
-        // Replace first selection if 2 already selected
+        // Replace first selection if 2 already selected (FIFO replacement)
         return [prev[1], hero];
       }
     });
   };
 
+  /**
+   * Checks if a superhero is currently selected.
+   * 
+   * @param {number} heroId - The ID of the hero to check
+   * @returns {boolean} True if the hero is selected, false otherwise
+   */
   const isHeroSelected = (heroId) => {
     return selectedHeroes.some(h => h.id === heroId);
   };
 
+  /**
+   * Switches to the comparison view when exactly 2 heroes are selected.
+   * 
+   * This function is called when the user clicks the "Compare Heroes" button.
+   * It only changes the view if exactly 2 heroes are currently selected.
+   */
   const handleCompare = () => {
     if (selectedHeroes.length === 2) {
       setCurrentView('comparison');
     }
   };
 
+  /**
+   * Returns to the table view and clears the selected heroes.
+   * 
+   * This function is called when the user clicks the "Back to Heroes Table" button
+   * from the comparison view. It resets both the view and the selection state.
+   */
   const handleBackToTable = () => {
     setCurrentView('table');
     setSelectedHeroes([]);
   };
 
+  /**
+   * Calculates which hero wins in a head-to-head comparison.
+   * 
+   * Compares six power stats (intelligence, strength, speed, durability, power, combat)
+   * between two heroes. Each stat comparison awards one point to the hero with the higher
+   * value. The hero with the most points wins. If the points are equal, it's a tie.
+   * 
+   * @param {Object} hero1 - The first superhero object
+   * @param {Object} hero1.powerstats - Object containing the hero's power statistics
+   * @param {Object} hero2 - The second superhero object
+   * @param {Object} hero2.powerstats - Object containing the hero's power statistics
+   * @returns {Object} An object containing the winner and the score
+   * @returns {Object|null} returns.winner - The winning hero object, or null if it's a tie
+   * @returns {string} returns.score - The score in "X-Y" format
+   */
   const calculateWinner = (hero1, hero2) => {
     const stats = ['intelligence', 'strength', 'speed', 'durability', 'power', 'combat'];
     let hero1Score = 0;
     let hero2Score = 0;
 
+    // Compare each stat and award points to the hero with the higher value
     stats.forEach(stat => {
       if (hero1.powerstats[stat] > hero2.powerstats[stat]) {
         hero1Score++;
@@ -56,15 +130,28 @@ function App() {
       }
     });
 
+    // Determine the winner based on total scores
     if (hero1Score > hero2Score) {
       return { winner: hero1, score: `${hero1Score}-${hero2Score}` };
     } else if (hero2Score > hero1Score) {
       return { winner: hero2, score: `${hero2Score}-${hero1Score}` };
     } else {
+      // It's a tie - return null for winner
       return { winner: null, score: `${hero1Score}-${hero2Score}` };
     }
   };
 
+  /**
+   * Renders the comparison view displaying two heroes side-by-side.
+   * 
+   * This view shows:
+   * - Hero images and names
+   * - A detailed comparison of all six power stats
+   * - Highlighting of winning stats for each hero
+   * - The final winner announcement or tie declaration
+   * 
+   * @returns {JSX.Element|null} The comparison view component, or null if not exactly 2 heroes selected
+   */
   const renderComparison = () => {
     if (selectedHeroes.length !== 2) return null;
 
@@ -79,6 +166,7 @@ function App() {
         </button>
         <h1>Superhero Comparison</h1>
 
+        {/* Hero cards displaying images and names */}
         <div className="comparison-container">
           <div className="hero-card">
             <img src={hero1.image} alt={hero1.name} className="hero-image" />
@@ -95,10 +183,12 @@ function App() {
           </div>
         </div>
 
+        {/* Stats comparison table with highlighting for winners */}
         <div className="stats-comparison">
           {stats.map(stat => {
             const stat1 = hero1.powerstats[stat];
             const stat2 = hero2.powerstats[stat];
+            // Determine which hero wins this stat comparison (or if it's a tie)
             const winner = stat1 > stat2 ? 'hero1' : stat1 < stat2 ? 'hero2' : 'tie';
 
             return (
@@ -117,6 +207,7 @@ function App() {
           })}
         </div>
 
+        {/* Final result section showing the overall winner or tie */}
         <div className="final-result">
           <h2>Final Result</h2>
           {result.winner ? (
@@ -135,6 +226,17 @@ function App() {
     );
   };
 
+  /**
+   * Renders the main table view displaying all superheroes.
+   * 
+   * This view includes:
+   * - A selection counter showing how many heroes are selected
+   * - Display of currently selected heroes
+   * - A button to compare the selected heroes (enabled only when 2 are selected)
+   * - A table showing all heroes with their stats and checkboxes for selection
+   * 
+   * @returns {JSX.Element} The table view component
+   */
   const renderTable = () => (
     <div className="table-view">
       <h1>Superheroes</h1>