Category: JavaScript

Sometimes, we want to add custom HTML attributes in our React JSX code.

In this article, we’ll look at how to add custom HTML attributes in our React JSX code.

How to Add Custom HTML Attributes in JSX

With React 16, we can add custom attributes natively.

For instance, we can write:

render() {
  return (
    <div data-foo="bar" />
  );
}

We can just add it straight into our HTML elements without doing anything special.

Use Children with React Stateless Functional Component in TypeScript

We can pass in the interface or type alias into the generic type argument of React.FunctionComponent to set the type for ur props.

As long as the alias or interface has the children prop, we can use the children prop.

For instance, we can write:

const Foo: React.FunctionComponent<FooProps> = props => (
  <div>
    <p>{props.bar}</p>
    <p>{props.children}</p>
  </div>
);

FooProps has the bar and children entries, so we can reference both in our component.

React.FC is the shorthand for React.FunctionComponent .

Before React 16.8, we use the React.StatelessComponent type instead.

For instance, we can write:

const Foo: React.StatelessComponent<{}> = props => (
  <div>{props.children}</div>
);

or:

const Foo : React.StatelessComponent<FooProps> = props => (
  <div>
    <p>{props.propInMyProps}</p>
    <p>{props.children}</p>
  </div>
);

React.SFC is the shorthand for React.StatelessComponent.

Conclusion

With React 16, we can add custom attributes natively.

Sometimes, we want to add a modal into our React app.

In this article, we’ll look at how to add a modal into our React app.

Create a React Modal

We can use React’s portal feature to render our component anywhere.

This way, we can create a modal that’s attached to whatever element we want.

For instance, we can write:

const ModalComponent = ({ children, onClose }) => {
  return createPortal(
    <div className="modal" onClick={onClose}>
      {children}
    </div>,
    document.getElementById("portal")
  );
};

class App extends React.Component {
  constructor(props) {
    super(props);

    this.state = {
      showModal: false
    };
  }

  render() {
    return (
      <div>
        <button onClick={() => this.setState({ showModal: true })}>
          Open modal
        </button>
        {this.state.modalOpen && (
          <ModalComponent onClose={() => this.setState({ showModal: false })}>
            <h1>modal content</h1>
          </ModalComponent>
        )}
      </div>
    );
  }
}

We create a ModalComponent component to let us nest content inside it.

We can do that since it takes the children component.

All we have to do is render the children prop.

We use React’s createPortal method to let us render the div anywhere we want.

In App , we created a button to let us open the modal.

To do that, we set the showModal state to true .

We also created a function that we pass into the onClose prop of ModalComponent so that showModal can be set to false .

This will close the modal since ModalComponent is only shown when showModal is true .

Conclusion

We can use React’s portal feature to render our component anywhere.

Sometimes, we want to registrar events listeners within the useEffect hook.

In this article, we’ll look at how to registrar events listeners within the useEffect hook.

Register Event Handlers within the React useEffect Hook

We can register events within the useEffect callback.

For instance, we can write:

const App = () => {
  const [userText, setUserText] = useState('');

  const handleUserKeyPress = useCallback(event => {
    const { key, keyCode } = event;
    if (keyCode === 32) {
      setUserText(prevUserText => `${prevUserText}${key}`);
    }
  }, []);

  useEffect(() => {
    window.addEventListener('keydown', handleUserKeyPress);

    return () => {
      window.removeEventListener('keydown', handleUserKeyPress);
    };
  }, [handleUserKeyPress]);

  return (
    <div>
      <p>{userText}</p>
    </div>
  );
}

We listen to the keypress event on the window.

If we press the space key, then the key code will be registered.

Then we can use that to append the state string with the key text.

We just keep appending the key code to the state string.

Conclusion

We can register events within the useEffect callback.

Sometimes, we want to use React hooks in a React class component.

In this article, we’ll look at how to use React hooks in a React class component.

Use React Hooks in a React Classic class Component

To use hooks in a class component, we can create a functional component that’s used as a higher-order component.

For instance, we can write:

const withHook = (Component) => {
  return WrappedComponent = (props) => {
    const someHookValue = useSomeHook();
    return <Component {...props} someHookValue={someHookValue} />;
  }
}

We used our useSomeHook hook in our withHook component.

Then we pass the hooks’s output value into the Component , which can be any component, including a class component.

Then we can use it by writing:

class Foo extends React.Component {
  render(){
    const { someHookValue } = this.props;
    return <div>{someHookValue}</div>;
  }
}

export default withHook(Foo);

We passed in Foo into our withHook higher-order component so that we can use our hook in the withHook HOC.

Conclusion

To use hooks in a class component, we can create a functional component that’s used as a higher-order component.

Sometimes, we want to add export to CSV button in a React table.

In this article, we’ll look at how to add export to CSV button in a React table.

How to add export to CSV button in a React table?

To add export to CSV button in a React table, we can use the react-csv library.

To install it, we run:

npm i react-csv

Then we add the button to the table by writing:

import React from "react";
import { useTable } from "react-table";
import { CSVLink } from "react-csv";

const csvData = [
  { firstName: "John", lastName: "Doe" },
  { firstName: "Jane", lastName: "Doe" }
];

const Table = ({ columns, data }) => {
  const {
    getTableProps,
    getTableBodyProps,
    headerGroups,
    rows,
    prepareRow
  } = useTable({
    columns,
    data
  });

  return (
    <table {...getTableProps()}>
      <thead>
        {headerGroups.map((headerGroup) => (
          <tr {...headerGroup.getHeaderGroupProps()}>
            {headerGroup.headers.map((column) => (
              <th {...column.getHeaderProps()}>{column.render("Header")}</th>
            ))}
          </tr>
        ))}
      </thead>
      <tbody {...getTableBodyProps()}>
        {rows.map((row, i) => {
          prepareRow(row);
          return (
            <tr {...row.getRowProps()}>
              {row.cells.map((cell) => {
                return <td {...cell.getCellProps()}>{cell.render("Cell")}</td>;
              })}
            </tr>
          );
        })}
      </tbody>
    </table>
  );
};

export default function App() {
  const columns = React.useMemo(
    () => [
      {
        Header: "Name",
        columns: [
          {
            Header: "First Name",
            accessor: "firstName"
          },
          {
            Header: "Last Name",
            accessor: "lastName"
          }
        ]
      }
    ],
    []
  );

  const data = React.useMemo(() => {
    return csvData.map((d) => Object.values(d));
  }, []);

  return (
    <>
      <CSVLink data={data}>Download me</CSVLink>
      <Table columns={columns} data={csvData} />;
    </>
  );
}

We create the Table component which calls the useTable hook with the columns and data props to return an object that has the properties we use to create the table.

Next, we add a CSV download link by using the CSVLink component.

We pass in a nested array as the value of the data prop so react-csv can generate the CSV from it.

We create the nested array by calling useMemo with a callback that returns the nested array which we create by calling csvData.map with a callback that returns the values in an array from each csvData entry with Object.values.

Now we should see a Download me button which we can click to download the CSV.

Conclusion

To add export to CSV button in a React table, we can use the react-csv library.