Tabs

React, Components, State, Children · Oct 13, 2021

Renders a tabbed menu and view component.

Define a Tabs component. Use the useState() hook to initialize the value of the bindIndex state variable to defaultIndex.
Define a TabItem component and filter children passed to the Tabs component to remove unnecessary nodes except for TabItem by identifying the function's name.
Define changeTab, which will be executed when clicking a <button> from the menu.
changeTab executes the passed callback, onTabClick, and updates bindIndex based on the clicked element.
Use Array.prototype.map() on the collected nodes to render the menu and view of the tabs.
Use the value of bindIndex to determine the active tab and apply the correct className.

.tab-menu > button {
  cursor: pointer;
  padding: 8px 16px;
  border: 0;
  border-bottom: 2px solid transparent;
  background: none;
}

.tab-menu > button.focus {
  border-bottom: 2px solid #007bef;
}

.tab-menu > button:hover {
  border-bottom: 2px solid #007bef;
}

.tab-content {
  display: none;
}

.tab-content.selected {
  display: block;
}

const TabItem = props => <div {...props} />;

const Tabs = ({ defaultIndex = 0, onTabClick, children }) => {
  const [bindIndex, setBindIndex] = React.useState(defaultIndex);
  const changeTab = newIndex => {
    if (typeof onTabClick === 'function') onTabClick(newIndex);
    setBindIndex(newIndex);
  };
  const items = children.filter(item => item.type.name === 'TabItem');

  return (
    <div className="wrapper">
      <div className="tab-menu">
        {items.map(({ props: { index, label } }) => (
          <button
            key={`tab-btn-${index}`}
            onClick={() => changeTab(index)}
            className={bindIndex === index ? 'focus' : ''}
          >
            {label}
          </button>
        ))}
      </div>
      <div className="tab-view">
        {items.map(({ props }) => (
          <div
            {...props}
            className={`tab-content ${
              bindIndex === props.index ? 'selected' : ''
            }`}
            key={`tab-content-${props.index}`}
          />
        ))}
      </div>
    </div>
  );
};

ReactDOM.createRoot(document.getElementById('root')).render(
  <Tabs defaultIndex="1" onTabClick={console.log}>
    <TabItem label="A" index="1">
      Lorem ipsum
    </TabItem>
    <TabItem label="B" index="2">
      Dolor sit amet
    </TabItem>
  </Tabs>
);

Tabs

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