LiveblocksSelectionPresence [template] v1.0.0

Multiplayer form field presence overlay using Liveblocks: an absolutely-positioned halo border and name pill that appears around an input when another user has focused it, driven by Liveblocks useOthers() and updateMyPresence().

Language

tsx

Body

    // Selection.tsx — overlay component (source: liveblocks/examples/nextjs-live-form-selection)
    import React from "react";
    import styles from "./Selection.module.css";

    export default function Selection({
      name,
      color,
    }: {
      name?: string;
      color?: string;
    }) {
      return (
        <div className={styles.selection}>
          <div
            className={styles.selection_border}
            style={{ borderColor: color }}
          />
          <div className={styles.selection_name} style={{ background: color }}>
            {name}
          </div>
        </div>
      );
    }

    // Selection.module.css
    /*
    .selection {
      position: absolute;
      top: 0; right: 0; bottom: 0; left: 0;
      pointer-events: none;          -- never steals clicks from the input
    }
    .selection_border {
      position: absolute;
      top: -5px; right: -5px; bottom: -5px; left: -5px;
      border-width: 5px;
      border-style: solid;
      border-radius: 11px;
      opacity: 0.2;                  -- halo effect: doesn't compete with focus ring
    }
    .selection_name {
      position: absolute;
      top: -29px; right: 0;
      height: 20px;
      padding: 0 6px;
      border-radius: 3px;
      color: white;
      font-size: 12px;
      line-height: 20px;
    }
    */

    // Selections.tsx — renders overlays for all peers focused on a given input
    import { useOthers } from "@liveblocks/react";

    const NAMES = ["Alice", "Bob", "Carol", "Dave"];
    const COLORS = ["#E03130", "#2F9E44", "#1971C2", "#F08C00"];

    function Selections({ id }: { id: string }) {
      const users = useOthers();
      return (
        <>
          {users.map(({ connectionId, presence }) => {
            if (presence.selectedId === id) {
              return (
                <Selection
                  key={connectionId}
                  name={NAMES[connectionId % NAMES.length]}
                  color={COLORS[connectionId % COLORS.length]}
                />
              );
            }
          })}
        </>
      );
    }

    // Usage — wrap each input in a relative container:
    function PresenceInput({ id, ...props }: React.InputHTMLAttributes<HTMLInputElement>) {
      const { updateMyPresence } = useMyPresence();
      return (
        <div style={{ position: "relative" }}>
          <input
            id={id}
            onFocus={() => updateMyPresence({ selectedId: id })}
            onBlur={() => updateMyPresence({ selectedId: null })}
            {...props}
          />
          <Selections id={id!} />
        </div>
      );
    }
  

Usage Notes

• Input container must be position:relative — the overlay latches to the nearest positioned ancestor.
• onBlur MUST clear selectedId to null — forgetting leaves ghost selections for peers.
• opacity: 0.2 on the halo border is intentional — below 0.4 to avoid fighting the input focus ring.
• For concurrent selections (two peers on same input), stacked 0.2 opacity borders blend visually; add a chip-count badge for accessibility.
• In production: replace the hardcoded NAMES/COLORS arrays with Liveblocks room metadata or user profile data.

Gotchas

• Without position:relative on the wrapper, the halo renders relative to a distant ancestor.
• Pair with a useWindowFocus hook that clears presence on window blur to prevent stale selections.
• For rich-text editors, replace selectedId (string) with a range object {blockId, from, to} and use bounding-box overlays.

LiveblocksSelectionPresence [template] v1.0.0

Multiplayer form field presence overlay using Liveblocks: an absolutely-positioned halo border and name pill that appears around an input when another user has focused it, driven by Liveblocks useOthers() and updateMyPresence().

Language

tsx

Body

    // Selection.tsx — overlay component (source: liveblocks/examples/nextjs-live-form-selection)
    import React from "react";
    import styles from "./Selection.module.css";

    export default function Selection({
      name,
      color,
    }: {
      name?: string;
      color?: string;
    }) {
      return (
        <div className={styles.selection}>
          <div
            className={styles.selection_border}
            style={{ borderColor: color }}
          />
          <div className={styles.selection_name} style={{ background: color }}>
            {name}
          </div>
        </div>
      );
    }

    // Selection.module.css
    /*
    .selection {
      position: absolute;
      top: 0; right: 0; bottom: 0; left: 0;
      pointer-events: none;          -- never steals clicks from the input
    }
    .selection_border {
      position: absolute;
      top: -5px; right: -5px; bottom: -5px; left: -5px;
      border-width: 5px;
      border-style: solid;
      border-radius: 11px;
      opacity: 0.2;                  -- halo effect: doesn't compete with focus ring
    }
    .selection_name {
      position: absolute;
      top: -29px; right: 0;
      height: 20px;
      padding: 0 6px;
      border-radius: 3px;
      color: white;
      font-size: 12px;
      line-height: 20px;
    }
    */

    // Selections.tsx — renders overlays for all peers focused on a given input
    import { useOthers } from "@liveblocks/react";

    const NAMES = ["Alice", "Bob", "Carol", "Dave"];
    const COLORS = ["#E03130", "#2F9E44", "#1971C2", "#F08C00"];

    function Selections({ id }: { id: string }) {
      const users = useOthers();
      return (
        <>
          {users.map(({ connectionId, presence }) => {
            if (presence.selectedId === id) {
              return (
                <Selection
                  key={connectionId}
                  name={NAMES[connectionId % NAMES.length]}
                  color={COLORS[connectionId % COLORS.length]}
                />
              );
            }
          })}
        </>
      );
    }

    // Usage — wrap each input in a relative container:
    function PresenceInput({ id, ...props }: React.InputHTMLAttributes<HTMLInputElement>) {
      const { updateMyPresence } = useMyPresence();
      return (
        <div style={{ position: "relative" }}>
          <input
            id={id}
            onFocus={() => updateMyPresence({ selectedId: id })}
            onBlur={() => updateMyPresence({ selectedId: null })}
            {...props}
          />
          <Selections id={id!} />
        </div>
      );
    }
  

Usage Notes

• Input container must be position:relative — the overlay latches to the nearest positioned ancestor.
• onBlur MUST clear selectedId to null — forgetting leaves ghost selections for peers.
• opacity: 0.2 on the halo border is intentional — below 0.4 to avoid fighting the input focus ring.
• For concurrent selections (two peers on same input), stacked 0.2 opacity borders blend visually; add a chip-count badge for accessibility.
• In production: replace the hardcoded NAMES/COLORS arrays with Liveblocks room metadata or user profile data.

Gotchas

• Without position:relative on the wrapper, the halo renders relative to a distant ancestor.
• Pair with a useWindowFocus hook that clears presence on window blur to prevent stale selections.
• For rich-text editors, replace selectedId (string) with a range object {blockId, from, to} and use bounding-box overlays.

Sources

• https://github.com/liveblocks/liveblocks

Source

• Repo: https://github.com/liveblocks/liveblocks
• Files:
  • examples/nextjs-live-form-selection/components/Selection.tsx (lines 1-24)
  • examples/nextjs-live-form-selection/components/Selection.module.css (lines 1-32)
  • examples/nextjs-live-form-selection/pages/index.tsx (lines 18-36)
• License: Apache-2.0