check if urls have the same origin

I have a function that runs before every API request to check if the request is from a valid origin.

I have an array of valid origins

const whitelist = [ 'a.com', 'b.co.uk' ]

const validOrigin = str => {
    const url = new URL( str )
    return whitelist.includes( url.host )
}

console.log(validOrigin('https://www.a.com'))

It returns false because of the www. I dont want to just add a copy with www. to the array of valid origins. I would like a way that covers this and everything else thats unexpected.