Blame for tasks/leetcode/environment/reference/clone/static/js/problemset.js

/* Problem-set interactions.
 *
 * Every filter, sort and page is expressed in the URL, so the page works with
 * scripting disabled: the popovers are <details>, the search box is a real
 * form field, and each control is a link. This file only adds the affordances
 * the captured page has on top of that — instant search submission, popover
 * dismissal, the topic-strip expander, the day countdown and company paging. */
(function () {
  "use strict";

  /* ---- header: mobile navigation and search ------------------------- */

  var navToggle = document.querySelector("[data-nav-toggle]");
  var nav = document.querySelector("[data-nav]");
  if (navToggle && nav) {
    navToggle.addEventListener("click", function () {
      var open = nav.classList.toggle("is-open");
      navToggle.setAttribute("aria-expanded", open ? "true" : "false");
    });
  }

  var navMenus = Array.prototype.slice.call(document.querySelectorAll("[data-navmenu]"));
  navMenus.forEach(function (menu) {
    menu.addEventListener("mouseenter", function () {
      navMenus.forEach(function (other) {
        if (other !== menu) other.open = false;
      });
      menu.open = true;
    });
    menu.addEventListener("mouseleave", function () {
      menu.open = false;
    });
  });

  var searchToggle = document.querySelector("[data-site-search-toggle]");
  var siteSearch = document.querySelector(".ap-search");
  if (searchToggle && siteSearch) {
    searchToggle.addEventListener("click", function () {
      siteSearch.classList.toggle("is-open");
      var field = siteSearch.querySelector("input");
      if (field && siteSearch.classList.contains("is-open")) {
        field.focus();
      }
    });
  }

  var siteSearchField = document.querySelector("[data-site-search]");
  if (siteSearchField) {
    siteSearchField.addEventListener("keydown", function (event) {
      if (event.key !== "Enter") {
        return;
      }
      event.preventDefault();
      var term = siteSearchField.value.trim();
      window.location.href = term
        ? "/problemset/?search=" + encodeURIComponent(term)
        : "/problemset/";
    });
  }

  /* ---- collapsible library rail ------------------------------------ */

  var railToggle = document.querySelector("[data-rail-toggle]");
  if (railToggle) {
    var railShell = railToggle.closest(".lc-shell, .ps");
    var storageKey = "leetcode-library-rail-collapsed";
    var setRail = function (collapsed) {
      if (!railShell) return;
      railShell.classList.toggle("is-rail-collapsed", collapsed);
      railToggle.setAttribute("aria-expanded", collapsed ? "false" : "true");
      railToggle.setAttribute("aria-label", collapsed ? "Expand library sidebar" : "Collapse library sidebar");
      var glyph = railToggle.querySelector("span");
      if (glyph) glyph.textContent = collapsed ? "›" : "‹";
    };
    setRail(window.sessionStorage.getItem(storageKey) === "1");
    railToggle.addEventListener("click", function () {
      var collapsed = !railShell.classList.contains("is-rail-collapsed");
      setRail(collapsed);
      window.sessionStorage.setItem(storageKey, collapsed ? "1" : "0");
    });
  }

  /* ---- filter popovers ---------------------------------------------- */

  var pops = Array.prototype.slice.call(document.querySelectorAll("[data-pop]"));
  pops.forEach(function (pop) {
    pop.addEventListener("toggle", function () {
      if (!pop.open) {
        return;
      }
      pops.forEach(function (other) {
        if (other !== pop) {
          other.open = false;
        }
      });
    });
  });
  document.addEventListener("click", function (event) {
    pops.forEach(function (pop) {
      if (pop.open && !pop.contains(event.target)) {
        pop.open = false;
      }
    });
  });
  document.addEventListener("keydown", function (event) {
    if (event.key === "Escape") {
      pops.forEach(function (pop) {
        pop.open = false;
      });
    }
  });

  /* ---- debounced search --------------------------------------------- */

  var controls = document.querySelector("[data-controls]");
  if (controls) {
    var field = controls.querySelector('input[name="search"]');
    if (field) {
      var timer = null;
      field.addEventListener("input", function () {
        window.clearTimeout(timer);
        timer = window.setTimeout(function () {
          controls.submit();
        }, 400);
      });
    }
  }

  /* ---- topic strip --------------------------------------------------- */

  var strip = document.querySelector("[data-topic-strip]");
  var expand = document.querySelector("[data-topic-expand]");
  if (strip && expand) {
    expand.addEventListener("click", function () {
      var expanded = strip.classList.toggle("is-expanded");
      expand.setAttribute("aria-expanded", expanded ? "true" : "false");
      expand.childNodes[0].nodeValue = expanded ? "Collapse" : "Expand";
    });
  }

  /* ---- daily countdown ----------------------------------------------- */

  var countdown = document.querySelector("[data-countdown]");
  if (countdown) {
    var deadline = new Date(countdown.getAttribute("data-deadline"));
    var tick = function () {
      var remaining = Math.max(0, Math.floor((deadline - new Date()) / 1000));
      var hours = Math.floor(remaining / 3600);
      var minutes = Math.floor((remaining % 3600) / 60);
      var seconds = remaining % 60;
      var pad = function (value) {
        return value < 10 ? "0" + value : String(value);
      };
      countdown.textContent =
        pad(hours) + ":" + pad(minutes) + ":" + pad(seconds) + " left";
    };
    tick();
    window.setInterval(tick, 1000);
  }

  /* ---- trending companies: paging and filtering ---------------------- */

  var list = document.querySelector("[data-company-list]");
  if (list) {
    var items = Array.prototype.slice.call(list.children);
    var pages =
      items.reduce(function (highest, item) {
        return Math.max(highest, Number(item.getAttribute("data-page")));
      }, 0) + 1;
    var page = 0;
    var term = "";

    var paint = function () {
      items.forEach(function (item) {
        var text = item.textContent.toLowerCase();
        var matches = !term || text.indexOf(term) !== -1;
        var onPage = term
          ? true
          : Number(item.getAttribute("data-page")) === page;
        item.hidden = !(matches && onPage);
      });
    };

    var prev = document.querySelector("[data-company-prev]");
    var next = document.querySelector("[data-company-next]");
    if (prev) {
      prev.addEventListener("click", function () {
        page = (page - 1 + pages) % pages;
        paint();
      });
    }
    if (next) {
      next.addEventListener("click", function () {
        page = (page + 1) % pages;
        paint();
      });
    }
    var companySearch = document.querySelector("[data-company-search]");
    if (companySearch) {
      companySearch.addEventListener("input", function () {
        term = companySearch.value.trim().toLowerCase();
        paint();
      });
    }
    paint();
  }
})();