Laravel validation rule "URL" does not pass empty value

Question

I have input text field whith validation rule :

public function rules()
{
    return [
        'field' => 'url',
    ];
}

It`s not required (field can be empty) but validation return an error.

Answer 1

Solve problem use "nullable":

public function rules()
{
    return [
        'field' => 'nullable|url',
    ];
}

Answer 2

when we submmitting values from js, like through a FormData, the value null could be submitted as string containing 'null', which may pass a nullable rule, cause further type check fail. so be sure to make this value be posted as '', literaly nothing, no a 'null' string