How to return a boolean if a document exists in MongoDB/Mongoose (node.js)

I am having problems. I have a collection called "Reviews" for my site, which are the reviews each user submits for recipes on the site. Before a user submits a review, I want to run a function that first checks whether he submitted a review already so that I can later ensure that they don't upvote a dish more than once. If there is a review already submitted by that user, it returns true, and if not, it returns false.

Here is the function I wrote:

let checkIfReviewExists = (userid, recipeId) => {

    console.log('First step...check if there is a review');

    Review

        .findOne({postedBy: userid, reviewOf: recipeId})

        .limit(1)

        .then((review) => {

            console.log('Within checkIfReviewExists....review is ' + review);

            if (review){
                console.log('Within checkIfReviewExtists...review exists and is ' + review);
                return true;
            }
            else {
                console.log('Within checkIfReviewExists....review does not exist and is ' + review);
                return false;
            }
        })

        .catch((err) => {
            console.log(err);
        });
};

However, whenever I run this function and store the return value in a variable, I keep on getting undefined.

let didReview = checkIfReviewExists(userid, recipeId);
//// If I console.log(didReview), I get "undefined"

I need didReview to be a boolean value in order to run another function. Can anyone help me out? What am I doing wrong?