Optional and mandatory values in JS functions

optionals

const mandatory = (
    message => {
        throw new Error(message);
    }
);


function f({
    optional = 'not provided',
    required = mandatory('the parameter "required" must not be null or undefined'),
} = {}) {

    return {
        'optional is': optional,
        'required is': required,
    };

}


console.log(f({required: 'asdf'})); //=> { 'optional is': 'not provided', 'required is': 'asdf' }


const g = (
    ({
        optional = 'not provided',
        required = mandatory('the parameter "required" must not be null or undefined'),
    } = {}) => ({
        'optional is': optional,
        'required is': required,
    })
)

console.log(g()); //=> Error: the parameter "required" must not be null or undefined