Simple JS+CSS omnibar.

omnibar.css

/* tiagorangel.com * If you use this, please credit me somewhere 

 * Make sure to set the following variables:
    --foreground: r, g, b
    --background: r, g, b

Example:
    --foreground: 13, 13, 14;
    --background: 255, 255, 255;
*/

.omnibar__wrapper {
    background-color: rgba(0, 0, 0, 0.5);
    display: flex;
    position: fixed;
    top: 0px;
    left: 0px;
    right: 0px;
    bottom: 0px;
    z-index: 1000;
    justify-content: center;
    padding-top: 20% !important;
    padding: 10px;
    overscroll-behavior: contain;
    transition: opacity .25s;
}

.omnibar {
    padding: 0;
    background: rgb(var(--background));
    max-width: 600px;
    max-height: min(400px, calc(100vh - 20% - 2rem));
    width: 95%;
    top: 20%;
    position: absolute;
    z-index: 2;
    display: flex;
    flex-direction: column;
    border-radius: 8px;
    transition: transform .25s, filter .25s;
    overflow: hidden;
    animation: omnibar-in .25s;
}

.omnibar__search {
    appearance: none;
    background: transparent;
    font-family: var(--font-sans);
    border: none;
    outline: none;
    padding: 1rem;
    color: rgba(var(--foreground), 0.9);
    font-size: 1rem;
    border-bottom: 1px solid rgba(var(--foreground), 0.1);
}

.omnibar__search[readonly] {
    cursor: default;
}

.omnibar__search[readonly]::placeholder {
    opacity: 1;
    color: rgb(var(--foreground));
}

.omnibar__results {
    overflow: auto;
    display: flex;
    flex-direction: column;
    gap: 2px;
    user-select: none;
}

.omnibar__section {
    display: flex;
    flex-direction: column;
}

.omnibar__section h4 {
    font-size: 0.8rem;
    padding: 0.2rem 1rem;
    color: rgba(var(--foreground), .85);
    margin-top: 0.5rem;
    font-family: var(--font-sans);
    margin: 5px 0px;
}

.omnibar__result {
    display: flex;
    align-items: center;
    width: 100%;
    padding: 0.6rem 1rem;
    color: rgba(var(--foreground), 0.95);
    text-decoration: none;
    border-left: 2px solid transparent;
    gap: 7px;
    cursor: pointer;
    transition: border-left-color .15s, background-color .15s
}

.omnibar__result svg {
    width: 20px;
    height: 20px;
    color: rgb(var(--foreground));
}

.omnibar__result p {
    margin: 0px;
}

.omnibar__result .omnibar__shortcut {
    margin-left: auto;
}

.omnibar__result.active {
    background-color: rgba(var(--foreground), 0.07);
    border-left-color: rgba(var(--foreground), 0.8);
}

@keyframes omnibar-in {
    from {
        opacity: 0;
        transform: scale(0.95);
        filter: blur(4px)
    }

    to {
        opacity: 1;
        transform: none;
        filter: none
    }
}

omnibar.js

const omnibar = {
  //                                 [{name (html allowed), shortcut(ex. ["⌘","⇧","H"]), icon_svg, action, id}]
  //                                 |
  //              [{name (optional), children}]
  //              |         { disableTyping, hideInputBorder, placeholder, noFilter }
  //              |         |

  open: function (sections, options) {
    let isOpen = true;
    let onClose, onSelection;

    let dataToFilter = [];

    const create = function (tag, classes) {
      const el = document.createElement(tag);
      if (classes) {
        classes.split(" ").forEach(function (name) {
          el.classList.add(name);
        });
      }

      return el;
    };

    const closeModal = function () {
      (onClose || function () {})();
      isOpen = false;
      wrapper.style.opacity = "0";
      modal.style.transform = "scale(0.95)";
      modal.style.filter = "blur(4px)";

      setTimeout(function () {
        wrapper.remove();
      }, 250);
    };

    const wrapper = create("div", "omnibar__wrapper");
    wrapper.style.opacity = "0";

    const modal = create("div", "omnibar");
    modal.style.transform = "scale(0.95)";
    modal.style.filter = "blur(4px)";

    wrapper.appendChild(modal);
    document.body.appendChild(wrapper);

    setTimeout(function () {
      wrapper.style.opacity = "1";
      modal.style.transform = "none";
      modal.style.filter = "none";
      input.focus();
    }, 1);

    const input = create("input", "omnibar__search");
    input.setAttribute("type", "search");
    input.setAttribute("name", "search");
    input.setAttribute("autocomplete", "off");
    input.setAttribute("spellcheck", "off");
    input.setAttribute(
      "placeholder",
      options?.placeholder || "Type a command or search"
    );

    if (options?.disableTyping) {
      input.setAttribute("readonly", "true");
    }

    if (options?.hideInputBorder) {
      input.style.borderBottom = "0px solid transparent";
    }

    modal.appendChild(input);

    const resultsWrap = create("div", "omnibar__results");
    modal.appendChild(resultsWrap);

    const focusIntoEl = function (childEl) {
      resultsWrap.querySelectorAll(".omnibar__result").forEach((e) => {
        e.classList.remove("active");
      });

      childEl.style.height = childEl.offsetHeight + "px";

      const childRect = childEl.getBoundingClientRect();
      const parentRect = resultsWrap.getBoundingClientRect();

      const isFullyVisible =
        childRect.top >= parentRect.top &&
        childRect.bottom <= parentRect.bottom;

      if (!isFullyVisible) {
        if (childRect.top < parentRect.top) {
          resultsWrap.scrollTo({
            top: resultsWrap.scrollTop - (parentRect.top - childRect.top),
            behavior: "smooth",
          });
        } else if (childRect.bottom > parentRect.bottom) {
          resultsWrap.scrollTo({
            top: resultsWrap.scrollTop + (childRect.bottom - parentRect.bottom),
            behavior: "smooth",
          });
        }
      }

      childEl.style.height = "unset";

      childEl.classList.add("active");
    };

    sections.forEach((section) => {
      const sectionEl = create("div", "omnibar__section");

      if (section.name) {
        const name = create("h4");
        name.innerText = section.name;
        sectionEl.appendChild(name);
      }

      section.children.forEach((child) => {
        const childEl = create("div", "omnibar__result");
        childEl.setAttribute("title", child.name);

        childEl.addEventListener("mouseover", function () {
          focusIntoEl(childEl);
        });

        childEl.addEventListener("mouseout", function () {
          resultsWrap.querySelectorAll(".omnibar__result").forEach((e) => {
            e.classList.remove("active");
          });
        });

        if (child.icon_svg) {
          const childIcon = create("span", "omnibar__icon");
          childIcon.innerHTML = child.icon_svg;
          childEl.appendChild(childIcon);
        }

        const childName = create("p");
        childName.innerHTML = child.name;

        childEl.appendChild(childName);

        if (child.shortcut && child.shortcut.length > 0) {
          const childShortcut = create("div", "omnibar__shortcut");
          childShortcut.innerHTML = `<code>${child.shortcut.join(
            "</code><code>"
          )}</code>`;
          childEl.appendChild(childShortcut);
        }

        childEl.addEventListener("click", function () {
          closeModal();

          (onSelection || function () {})(child.id);
          (child.action || function () {})(child.id);
        });

        sectionEl.appendChild(childEl);
        dataToFilter.push({
          id: child.id,
          name: child.name,
        });
      });

      resultsWrap.appendChild(sectionEl);
    });

    document.addEventListener("keyup", function (e) {
      if (!isOpen) {
        return;
      }

      if (e.key === "Escape") {
        closeModal();
      }
    });

    document.addEventListener("click", function (e) {
      if (!isOpen) {
        return;
      }

      if (e.target === wrapper) {
        closeModal();
      }
    });

    if (!options?.noFilter) {
      input.addEventListener("input", function () {
        resultsWrap
          .querySelectorAll(".omnibar__section, .omnibar__result")
          .forEach((e) => {
            e.style.display = "flex";
          });

        resultsWrap.querySelectorAll(".omnibar__result").forEach((e) => {
          if (
            !e
              .querySelector("p")
              .innerText.toLowerCase()
              .includes(input.value.trim().toLowerCase())
          ) {
            e.style.display = "none";
          }
        });

        document.querySelectorAll(".omnibar__section").forEach((section) => {
          let allHidden = Array.from(
            section.querySelectorAll(".omnibar__result")
          ).every(function (result) {
            return result.offsetParent === null;
          });

          if (allHidden) {
            section.style.display = "none";
          }
        });
      });
    }

    input.addEventListener("keydown", function (e) {
      if (e.key == "ArrowDown" || e.key == "ArrowLeft" || e.key == "Tab") {
        e.preventDefault();

        let lastIndex = -1;

        document.querySelectorAll(".omnibar__result").forEach((e, i) => {
          if (e.classList.contains("active")) {
            lastIndex = i;
            e.classList.remove("active");
          }
        });

        focusIntoEl(
          document.querySelectorAll(".omnibar__result")[lastIndex + 1] ||
            document.querySelectorAll(".omnibar__result")[0]
        );
      }

      if (
        e.key == "ArrowUp" ||
        e.key == "ArrowRight" ||
        (e.shiftKey && e.key == "Tab")
      ) {
        e.preventDefault();

        let lastIndex = -1;

        document.querySelectorAll(".omnibar__result").forEach((e, i) => {
          if (e.classList.contains("active")) {
            lastIndex = i;
            e.classList.remove("active");
          }
        });

        focusIntoEl(
          document.querySelectorAll(".omnibar__result")[lastIndex - 1] ||
            document.querySelectorAll(".omnibar__result")[
              document.querySelectorAll(".omnibar__result").length - 1
            ]
        );
      }
      if (e.key == "Enter") {
        e.preventDefault();

        if (resultsWrap.querySelector(".omnibar__results")) {
          (
            resultsWrap.querySelectorAll(".omnibar__result")[0] ||
            resultsWrap.querySelectorAll(".omnibar__result.active")[0]
          ).click();
        } else {
          closeModal();
          (onSelection || function () {})(input.value);
        }
      }
    });

    return {
      close: closeModal,
      onClose: function (listener) {
        onClose = listener;
      },
      onSelection: function (listener) {
        onSelection = listener;
      },
      onQuery: function (listener) {
        input.addEventListener("keypress", function () {
          listener(input.value);
        });
      },
      onSubmitText: function (listener) {
        input.addEventListener("keydown", function (e) {
          if (e.key == "Enter") {
            listener(input.value);
          }
        });
      },
      asyncEvents: {
        awaitClose: function () {
          return new Promise((resolve) => {
            onClose = resolve;
          });
        },
        awaitSelection: function () {
          return new Promise((resolve) => {
            onSelection = resolve;
          });
        },
        awaitSubmitText: function () {
          return new Promise((resolve) => {
            input.addEventListener("keypress", function (e) {
              if (e.key == "Enter") {
                resolve(input.value);
              }
            });
          });
        },
      },
    };
  },
  prompt: function (prompt, options) {
    return new Promise((resolve) => {
      let query = "";
      let ended;

      const bar = omnibar.open([], {
        placeholder: prompt,
        noFilter: true,
        hideInputBorder: true,
      });
      bar.onQuery(function (q) {
        query = q;
      });
      bar.onSubmitText(function (q) {
        query = q;
        ended = true;
        
        resolve(query.trim());
      });
      bar.onClose(function () {
        setTimeout(function () {
          if (ended) {
            return;
          }
          resolve(false);
        }, 1);
      });
    });
  },
};

window.omnibar = omnibar;

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