whoogle-search/app/static/js/header.js

document.addEventListener("DOMContentLoaded", () => {
    const advSearchToggle = document.getElementById("adv-search-toggle");
    const advSearchDiv = document.getElementById("adv-search-div");
    const searchBar = document.getElementById("search-bar");
    const countrySelect = document.getElementById("result-country");
    const arrowKeys = [37, 38, 39, 40];
    let searchValue = searchBar.value;

    countrySelect.onchange = () => {
        let str = window.location.href;
        n = str.lastIndexOf("/search");
        if (n > 0) {
            str = str.substring(0, n) +
                `/search?q=${searchBar.value}&country=${countrySelect.value}`;
            window.location.href = str;
        }
    }

    const toggleAdvancedSearch = on => {
        if (on) {
            advSearchDiv.style.maxHeight = "70px";
        } else {
            advSearchDiv.style.maxHeight = "0px";
        }
        localStorage.advSearchToggled = on;
    }

    toggleAdvancedSearch(JSON.parse(localStorage.advSearchToggled));
    advSearchToggle.onclick = () => {
        toggleAdvancedSearch(advSearchToggle.checked);
    }

    searchBar.addEventListener("keyup", function(event) {
        if (event.keyCode === 13) {
            document.getElementById("search-form").submit();
        } else if (searchBar.value !== searchValue && !arrowKeys.includes(event.keyCode)) {
            searchValue = searchBar.value;
            handleUserInput();
        }
    });
});