PUG with javascript

If I have the following piece of code

script.
    function getProductParams(params) {
        return JSON.parse(localStorage.getItem(params));
    }

each product in products
    -var getVariable = getProductParams("ids");

This piece of code doesn't work, I'm guessing that - is on server side, while script. is on clients? How can I access a variable from localStorage in pug and use it for comparison with variables received from server.

I want to make something like this

script.
    function getProductParams(params) {
        return JSON.parse(localStorage.getItem(params));
    }

each product in products
    -var getVariable = getProductParams("ids");
    -if (getVariable.includes(#{product._id}) {
        // create the element in html
    -} else {
    - // call next product and compare if we have it
    -}