propType [name] is not required, but has no corresponding defaultProp declaration

[ghost]

I am using Flow for type checking, and I have something like this:

type Props = {
  name?: ?string, // this means that "name" is NOT mandatory, and its value can be **null** or **undefined**
};

So, my question is, should I get this linting error? Is this the desired behavior?

[jseminck]

I would say this is as expected. Since the prop is not required, you should specify a default value. You can decide to set it to null or undefined by default.

[ghost]

I see. Thank you

[AlexanderNaiden]

I didn't understand what should I do in my case (it's also shows eslint error: propType "isSmall" is not required, but has no corresponding defaultProp declaration. (react/require-default-props)):

type SwitcherProps = {
    isChecked: boolean,
    action: () => void,
    isSmall?: boolean
}

export const Switcher = (props: SwitcherProps) => {
    return (       
        <label className={"switcher ".concat(props.isSmall ? "small" : "")}>
            <input type="checkbox" checked={props.isChecked} className="input" />
            <span role="presentation" className="slider" onClick={props.action} />
        </label>
    );
};

[ljharb]

@AlexanderNaiden add:

Switcher.defaultProps = {
  isSmall: false,
};

[arel]

The error message is confusing because it's singular instead of plural.

(and... #2063 was posted just 2 hours ago!)

[tanishbansal20]

I fixed this issue using the default prop

  static defaultProps = {
    actions: {
      function_name: () => null,
    },
  }