How to get the object key it has the value

I have a filter component which user can choose any data to filter so I store this data in state.when I want to create a params for query some of the field not choosen by user I only wanna get the one which has value here is the code ;

function createParams(params = {}) {
    let result = "?";
    for (let key in params) {
        result += `${key}=${params[key]}&`;
    }
    return result;
}

export async function callApi(params) {
    const parameters = createParams(params);
    try {
        const response = await fetch(URL+ parameters);
        const res = await response.json();
        return res;
    } catch (error) {
        console.error(error)
        throw error;
    }
}

export const requestProperties = (params) => callApi(params);

const requestedParams = {type:"Fiat", model:"500", color:""};

I only want to get the type and model because it has been choosen by user to filter. I dont wanna include the colour

Thank you..:)