Passing booleans as Props to a Component in React

Passing booleans as Props to a Component in React #

To pass a boolean as props to a component in React, wrap the boolean in curly braces, e.g. <Child bool={true} />. All props you pass to a component that are not of type string have to be wrapped in curly braces.

App.js

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function Child({bool}) {
  console.log(bool);

  return <div>{bool && <h2>Hello world</h2>}</div>;
}

export default function App() {
  return (
    <div>
      <Child bool={true} />
    </div>
  );
}

We passed a bool prop to a component. Notice that we had to wrap the prop in curly braces.

You might also see examples online that pass boolean props using just the name of the prop.

App.js

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function Child({bool}) {
  console.log(bool);

  return <div>{bool && <h2>Hello world</h2>}</div>;
}

export default function App() {
  return (
    <div>
      <Child bool />
    </div>
  );
}

Passing the prop as bool is the same as bool={true}. However, if you are passing a dynamic value (from a variable) or a false boolean as prop, you have to explicitly specify it like in the first code snippet.

All props that are not of type string have to be wrapped in curly braces when passed.

The curly braces syntax lets React know that there is an expression it has to evaluate.

You can then destructure and use the bool prop in the child component.

The same approach has to be used when passing an object or an array as props.

App.js

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function Child({bool, obj, arr}) {
  console.log(bool);

  return (
    <div>
      <div>{bool && <h2>Hello world</h2>}</div>

      <h2>name: {obj.name}</h2>

      <h2>color: {arr[0]}</h2>
    </div>
  );
}

export default function App() {
  return (
    <div>
      <Child bool={true} obj={{id: 1, name: 'Bob'}} arr={['blue', 'green']} />
    </div>
  );
}

Notice that we when passing an object as props, we use 2 sets of curly braces.

This first set marks the beginning of the expression, and the second set is the actual object.

Strings are the only values you can pass as props without wrapping them in curly braces.

App.js

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function Child({str, bool, obj, arr}) {
  console.log(bool);

  return (
    <div>
      <h2>{str}</h2>

      <div>{bool && <h2>Hello world</h2>}</div>

      <h2>name: {obj.name}</h2>

      <h2>color: {arr[0]}</h2>
    </div>
  );
}

export default function App() {
  return (
    <div>
      <Child
        str="Some content"
        bool={true}
        obj={{id: 1, name: 'Bob'}}
        arr={['blue', 'green']}
      />
    </div>
  );
}

You could also wrap the string in curly braces to be consistent, but that's not necessary.

App.js

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function Child({str, bool, obj, arr}) {
  console.log(bool);

  return (
    <div>
      <h2>{str}</h2>

      <div>{bool && <h2>Hello world</h2>}</div>

      <h2>name: {obj.name}</h2>

      <h2>color: {arr[0]}</h2>
    </div>
  );
}

export default function App() {
  return (
    <div>
      <Child
        str={'Some content'}
        bool={true}
        obj={{id: 1, name: 'Bob'}}
        arr={['blue', 'green']}
      />
    </div>
  );
}

If you use a template string or some logic to construct the string, you must wrap it in curly braces.

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Passing booleans as Props to a Component in React

Passing booleans as Props to a Component in React #

Borislav Hadzhiev