React Hook(1) - useState

// useInput Hook
// 초기값, 검증 함수
const useInput = (initialValue, validator) => {
  const [value, setValue] = useState(initialValue);
  const onChange = (event) => {
    const {
      target: { value }
    } = event;
    let willUpdate = true;
    if (typeof validator === "function") {
      willUpdate = validator(value);
    }
    if (willUpdate) {
      setValue(value);
    }
  };
  return { value, onChange };
};

export default function App() {
  const maxLen = (value) => value.length <= 10;
  const name = useInput("Mr.", maxLen);
  return (
    <div className="App">
      <h1>Hello</h1>
      <input placeholder="Name" {...name} />
    </div>
  );
}

// useTabs
const useTabs = (initialTab, allTabs) => {
  if (!allTabs || Array.isArray(allTabs)) {
    return;
  }
  const [currentIndex, setCurrentIndex] = useState(initialTab);
  return {
    currentItem: allTabs[currentIndex],
    changeItem: setCurrentIndex
  };
};

const content = [
  {
    tab: "Section 1",
    content: "I'm the content of the Section 1"
  },
  {
    tab: "Section 2",
    content: "I'm the content of the Section 2"
  }
];

const App = () => {
  const { currentItem, changeItem } = useTabs(0, content);

  return (
    <div className="App">
      {content.map((section, index) => (
        <button onClick={() => changeItem(index)}>{section.tab}</button>
      ))}
      <div>{currentItem.content}</div>
    </div>
  );
};

export default App;