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
    -}

Solution

The simple answer is that you can't do this. LocalStorage is exactly that - local. Your server can't directly access it unless you explicitly pass it back using some other format/method.

What your server can access easily is the cookie. If you store the data in the cookie and use cookie-parser then you can handle this list quickly. This use case is exactly why cookies exist.

Another option would be to pass the data to the server in the body of a POST request, but your question doesn't provide a lot of information as to what exactly you're doing and if this is an option or not.

It would also be much easier for you to accomplish all of the sorting and filtering in your route instead of the pug template. That way you have full request to the cookie, request body, etc. directly and you don't have to pass that down to the template too. Then, when your template gets the list it's a really simple matter to render it:

each product in products
  //create the element in html