learning-jsdp/ch07/decorators_interface_2.html at main · addyosmani/learning-jsdp · GitHub

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<!DOCTYPE html>
<html>
  <head>
    <meta charset="UTF-8" />
    <title>MacBook Decorators Example</title>
  </head>
  <body>
    <h1>MacBook Decorators Example</h1>
    <form id="decoratorForm">
      <label for="engravingCheckbox">Engraving</label>
      <input type="checkbox" id="engravingCheckbox" />
      <br />
      <label for="parallelsCheckbox">Parallels</label>
      <input type="checkbox" id="parallelsCheckbox" />
      <br />
      <label for="ramSelect">RAM:</label>
      <select id="ramSelect">
        <option value="4">4GB</option>
        <option value="8">8GB</option>
      </select>
      <br />
      <label for="caseCheckbox">Case</label>
      <input type="checkbox" id="caseCheckbox" />
      <br />
      <button type="submit">Create MacBook</button>
    </form>
    <div id="macBookOutput"></div>

    <script>
      // Interface constructor
      function Interface(name, methods) {
        if (arguments.length !== 2) {
          throw new Error('Interface constructor called with ' + arguments.length + ' arguments, but expected exactly 2.');
        }
        this.name = name;
        this.methods = [];
        for (let i = 0; i < methods.length; i++) {
          if (typeof methods[i] !== 'string') {
            throw new Error('Interface constructor expects method names to be passed in as strings.');
          }
          this.methods.push(methods[i]);
        }
      }

      // Ensure implementation of an interface
      Interface.ensureImplements = function (object, ...interfaces) {
        if (arguments.length < 2) {
          throw new Error('Function Interface.ensureImplements called with ' + arguments.length + ' arguments, but expected at least 2.');
        }

        for (let i = 0; i < interfaces.length; i++) {
          const interfaceInstance = interfaces[i];
          if (interfaceInstance.constructor !== Interface) {
            throw new Error('Function Interface.ensureImplements expects arguments two and above to be instances of Interface.');
          }

          for (let j = 0; j < interfaceInstance.methods.length; j++) {
            const method = interfaceInstance.methods[j];
            if (!object[method] || typeof object[method] !== 'function') {
              throw new Error('Function Interface.ensureImplements: object does not implement the ' + interfaceInstance.name + ' interface. Method ' + method + ' was not found.');
            }
          }
        }
      };

      // Define MacBook interface
      const MacBook = new Interface('MacBook', [
        'addEngraving',
        'addParallels',
        'add4GBRam',
        'add8GBRam',
        'addCase',
        'getPrice',
      ]);

      // MacBook Pro class
      class MacBookPro {
        addEngraving() {
          return 'Added Engraving';
        }

        addParallels() {
          return 'Added Parallels';
        }

        add4GBRam() {
          return 'Added 4GB RAM';
        }

        add8GBRam() {
          return 'Added 8GB RAM';
        }

        addCase() {
          return 'Added Case';
        }

        getPrice() {
          return 900.0;
        }
      }

      // Abstract Decorator class
      class MacBookDecorator {
        constructor(macbook) {
          Interface.ensureImplements(macbook, MacBook);
          this.macbook = macbook;
        }

        addEngraving() {
          return this.macbook.addEngraving();
        }

        addParallels() {
          return this.macbook.addParallels();
        }

        add4GBRam() {
          return this.macbook.add4GBRam();
        }

        add8GBRam() {
          return this.macbook.add8GBRam();
        }

        addCase() {
          return this.macbook.addCase();
        }

        getPrice() {
          return this.macbook.getPrice();
        }
      }

      // Decorator form
      const decoratorForm = document.getElementById('decoratorForm');
      decoratorForm.addEventListener('submit', function (event) {
        event.preventDefault();

        const engravingCheckbox = document.getElementById('engravingCheckbox');
        const parallelsCheckbox = document.getElementById('parallelsCheckbox');
        const ramSelect = document.getElementById('ramSelect');
        const caseCheckbox = document.getElementById('caseCheckbox');

        let macBook = new MacBookPro();

        if (engravingCheckbox.checked) {
          macBook = new MacBookDecorator(macBook);
        }

        if (parallelsCheckbox.checked) {
          macBook = new MacBookDecorator(macBook);
        }

        if (ramSelect.value === '4') {
          macBook = new MacBookDecorator(macBook);
        }

        if (caseCheckbox.checked) {
          macBook = new MacBookDecorator(macBook);
        }

        displayMacBook(macBook);
      });

      // Display MacBook details
      function displayMacBook(macBook) {
        const output = document.getElementById('macBookOutput');
        output.innerHTML = `
          <p>${macBook.addEngraving()}</p>
          <p>${macBook.addParallels()}</p>
          <p>${macBook.add4GBRam()}</p>
          <p>${macBook.add8GBRam()}</p>
          <p>${macBook.addCase()}</p>
          <p><strong>Price:</strong> $${macBook.getPrice()}</p>
        `;
      }
    </script>
  </body>
</html>