React Conditional Rendering

In React, you can conditionally render components.

There are several ways to do this.

if Statement

We can use the if JavaScript operator to decide which component to render.

Example:

We'll use these two components:

function MissedGoal() {
  return <h1>MISSED!</h1>;
}

function MadeGoal() {
  return <h1>Goal!</h1>;
}

Example:

Now, we'll create another component that chooses which component to render based on a condition:

function Goal(props) {
  const isGoal = props.isGoal;
  if (isGoal) {
    return <MadeGoal/>;
  }
  return <MissedGoal/>;
}

const root = ReactDOM.createRoot(document.getElementById('root'));
root.render(<Goal isGoal={false} />);

Try changing the isGoal attribute to true:

Example:

const root = ReactDOM.createRoot(document.getElementById('root'));
root.render(<Goal isGoal={true} />);

Logical && Operator

Another way to conditionally render a React component is by using the && operator.

Example:

We can embed JavaScript expressions in JSX by using curly braces:

function Garage(props) {
  const cars = props.cars;
  return (
    <>
      <h1>Garage</h1>
      {cars.length > 0 &&
        <h2>
          You have {cars.length} cars in your garage.
        </h2>
      }
    </>
  );
}

const cars = ['Ford', 'BMW', 'Audi'];
const root = ReactDOM.createRoot(document.getElementById('root'));
root.render(<Garage cars={cars} />);

If cars.length > 0 is equates to true, the expression after && will render.

Try emptying the cars array:

Example:

const cars = [];
const root = ReactDOM.createRoot(document.getElementById('root'));
root.render(<Garage cars={cars} />);

Ternary Operator

Another way to conditionally render elements is by using a ternary operator.

condition ? true : false

We will go back to the goal example.

Example:

Return the MadeGoal component if isGoal is true, otherwise return the MissedGoal component:

function Goal(props) {
  const isGoal = props.isGoal;
  return (
    <>
      { isGoal ? <MadeGoal/> : <MissedGoal/> }
    </>
  );
}

const root = ReactDOM.createRoot(document.getElementById('root'));
root.render(<Goal isGoal={false} />);

To learn more, see the ternary operator section.