Introduction

In this lab, we will be creating a Tabs component in React that allows users to switch between different content views by clicking on a menu. We will be using the useState() hook to manage the active tab index and the map() method to render the tab menu and content view. By the end of this lab, you will have a better understanding of how to build reusable components in React using state and props.

Tabs

index.html and script.js have already been provided in the VM. In general, you only need to add code to script.js and style.css.

To render a tabbed menu and view component, follow these steps:

1. Define a Tabs component. Use the useState() hook to set the bindIndex state variable to defaultIndex.
2. Define a TabItem component and filter the children passed to the Tabs component to remove any unnecessary nodes except for TabItem. You can do this by identifying the function's name.
3. Define a function called changeTab. This function will be executed when a user clicks a <button> from the menu.
4. changeTab executes the passed callback, onTabClick, and updates bindIndex based on the clicked element.
5. Use Array.prototype.map() on the collected nodes to render the menu and view of the tabs.
6. Use the value of bindIndex to determine the active tab and apply the correct className.

Here is the CSS code to style the tabbed menu and view:

.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;
}

Here is the JavaScript code to implement the Tabs component:

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>
  );
};

Finally, here is an example of how to use the Tabs component:

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>
);

Please click on 'Go Live' in the bottom right corner to run the web service on port 8080. Then, you can refresh the Web 8080 Tab to preview the web page.

Summary

Congratulations! You have completed the Tabs lab. You can practice more labs in LabEx to improve your skills.

🚀 Practice Now: Building Reusable React Tabs Component

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