Library/ 08 word-loopText

Word Loop

One word in your headline keeps changing its mind.

It plays on load: press Replay to see it again

Fullscreen

Settings

words

interval2500

duration600

What it does

Word Loop is a text animation ready for your AI assistant, React or plain JavaScript, with no dependencies. Also called word rotate, rotating text or flip words.

A single word flips through a list of alternatives, each one rising into place as the previous slides away. The sentence around it never shifts, the loop pauses offscreen, and screen readers hear the full list once.

Documentation

One copy gives an assistant everything it needs: the complete code, every option and every pitfall. Paste it in Claude, Cursor or ChatGPT and say where the effect goes; it adapts the integration to your stack, not the code.

Copy the prompt

Ask for it

For instance: Add this word loop effect to the hero of my home page.

What it sends

Markdown

# Foundry44 · Word Loop

One word in a sentence cycles through alternatives with a vertical swap.

Add this component to my project. Pick the setup below that matches my project and follow only that one. When it uses the code at the end, keep its logic as written (it is self-contained, with no dependencies) and adapt only the integration: JavaScript instead of TypeScript if the project has none, file names, imports, how it starts.

## Markup it expects

The element marked `data-f44="word-loop"`, with this structure inside. Texts, images and the number of items are the demo's: use mine. The `data-f44-*` attributes set options for the ready-made script only; with the code, pass the same options to `wordLoop()` or as props.

```html
<span data-f44="word-loop">slow mornings, long shade, wet winters, quiet streets</span>
```

## Options

| Option | Attribute | Type | Default | Description |
|---|---|---|---|---|
| `words` | `data-f44-words` | `string[] | string` | `[]` | The words to cycle through, as an array or a comma-separated string. Defaults to the element's text, split on commas. |
| `interval` | `data-f44-interval` | `number` | `2500` | Time in ms each word stays before the next one replaces it. |
| `duration` | `data-f44-duration` | `number` | `600` | Time in ms for one swap. |

## Setup

- **Plain HTML, no build step**: don't paste the code below. Load the ready-made script once, at the end of `<body>`: `<script src="https://foundry44.dev/demos/word-loop/word-loop.js" defer></script>` (or download that file and serve it with the page). It starts itself on every `data-f44="word-loop"` element and reads the `data-f44-*` attributes above.
- **React / Next.js with shadcn/ui** (the project has a `components.json`; otherwise, see the next line): `npx shadcn@latest add https://foundry44.dev/r/word-loop.json` writes `lib/word-loop-core.ts` and `components/ui/word-loop.tsx`, then use `<WordLoop />` with the options as props.
- **React / Next.js from npm** (no shadcn/ui, or the user prefers a package): `npm install @foundry44/react` (or the project's package manager), then `import { WordLoop } from "@foundry44/react"` with the options as props. With a bundler and no React: `@foundry44/core`, then `import { wordLoop } from "@foundry44/core/word-loop"`.
- **React / Next.js by hand**: save the code below as `lib/word-loop-core.ts` and import it from there (`@/lib/word-loop-core` where that alias exists). Don't name it `word-loop.ts` next to a `WordLoop.tsx`: on macOS and Windows the two names collide. In a component marked `"use client"`, call `wordLoop(ref.current, options)` in a `useEffect` and return `instance.destroy` as its cleanup; call `instance.update(options)` when options change.
- **Any other stack**: create on mount with `wordLoop(element, options)`, `update(options)` when they change, `destroy()` on unmount.

Only the ready-made script finds `data-f44` elements and starts them by itself. Pasted code does not: call `wordLoop(element)` on each element.

## Pitfalls

- Respects prefers-reduced-motion: keep that behaviour.
- The element keeps the width of the longest word: in the middle of a sentence, shorter words leave a gap after them. The effect reads best at the end of a line.
- Before the script runs, the element shows its own text. Writing the words there, separated by commas, gives a readable fallback.
- In React, pass the words as `words`, not as children: the element's content is rebuilt.
- Screen readers hear the whole list once, separated by commas, not each swap.

## Code: `word-loop-core.ts`

```ts
// Copyright (c) 2026 Foundry44 · MIT License (SPDX-License-Identifier: MIT)
/**
 * Foundry44 — word-loop
 * One word in a sentence cycles through a list of alternatives. The current
 * word slides up and out behind an invisible edge while the next one rises
 * from below. The element keeps the width of the longest word, so the rest of
 * the sentence never shifts. The loop pauses while the element is offscreen.
 *
 * Self-contained: no imports, so this file can be copied as-is.
 */

export interface WordLoopOptions {
  /** The words to cycle through, as an array or a comma-separated string. Defaults to the element's text, split on commas. */
  words?: string[] | string;
  /** Time in ms each word stays before the next one replaces it. @range 800 8000 100 */
  interval?: number;
  /** Time in ms for one swap. @range 150 2000 50 */
  duration?: number;
}

export interface WordLoopInstance {
  update(options: WordLoopOptions): void;
  destroy(): void;
}

export const wordLoopDefaults: Required<WordLoopOptions> = {
  words: [],
  interval: 2500,
  duration: 600,
};

const EASE_OUT = "cubic-bezier(0.23, 1, 0.32, 1)";
// Clips the top and bottom just outside the line, so descenders survive a tight line-height;
// the sides are extended so italic overhangs are never cut.
const MASK_CLIP = "inset(-0.08em -0.25em)";
// Well past 100%: with a tight line-height, descenders and ascenders overflow the line box,
// and a hidden word must clear the mask with them.
const BELOW = "translateY(130%)";
const ABOVE = "translateY(-130%)";

const toList = (words: string[] | string) =>
  (typeof words === "string" ? words.split(",") : words).map((word) => word.trim()).filter(Boolean);

export function wordLoop(el: HTMLElement, options: WordLoopOptions = {}): WordLoopInstance {
  let opts = { ...wordLoopDefaults, ...options };

  if (typeof window === "undefined") return { update() {}, destroy() {} };
  // Reduced motion keeps the rotation but drops the movement: words crossfade in place.
  const reduced = window.matchMedia?.("(prefers-reduced-motion: reduce)").matches === true;
  const property = reduced ? "opacity" : "transform";
  const enterValue = reduced ? "0" : BELOW;
  const exitValue = reduced ? "0" : ABOVE;
  const shownValue = reduced ? "1" : "none";

  const originalStyle = el.getAttribute("style");
  // The original nodes are put back as-is on destroy() (frameworks keep references to them).
  const originalNodes = Array.from(el.childNodes);
  const textWords = toList(el.textContent ?? "");
  const currentList = () => {
    const list = toList(opts.words);
    return list.length ? list : textWords;
  };

  let spans: HTMLSpanElement[] = [];
  let listKey = "";
  let index = 0;
  let timer = 0;
  let visible = false;
  let observer: IntersectionObserver | null = null;

  // Every word sits in the same grid cell, so the element takes the width of the
  // longest one and swapping never reflows the sentence around it.
  el.style.display = "inline-grid";
  el.style.justifyItems = "start";
  el.style.clipPath = MASK_CLIP;

  const build = () => {
    const list = currentList();
    listKey = list.join("\n");
    index = 0;
    el.replaceChildren();
    // Screen readers get the whole list once instead of hearing every swap.
    const label = document.createElement("span");
    label.textContent = list.join(", ");
    label.style.cssText =
      "position:absolute;width:1px;height:1px;overflow:hidden;clip-path:inset(50%);white-space:nowrap";
    el.appendChild(label);
    spans = list.map((word, i) => {
      const span = document.createElement("span");
      span.textContent = word;
      span.setAttribute("aria-hidden", "true");
      span.style.gridArea = "1 / 1";
      span.style.whiteSpace = "nowrap";
      span.style.setProperty(property, i === 0 ? shownValue : enterValue);
      el.appendChild(span);
      return span;
    });
  };

  const swap = () => {
    const from = spans[index];
    index = (index + 1) % spans.length;
    const to = spans[index];
    if (!from || !to) return;
    const transition = `${property} ${opts.duration}ms ${EASE_OUT}`;
    from.style.transition = transition;
    from.style.setProperty(property, exitValue);
    // Jump the incoming word below the edge first, so it always rises from the bottom.
    to.style.transition = "none";
    to.style.setProperty(property, enterValue);
    void to.offsetHeight;
    to.style.transition = transition;
    to.style.setProperty(property, shownValue);
    schedule();
  };

  const schedule = () => {
    window.clearTimeout(timer);
    timer = 0;
    if (visible && spans.length > 1) timer = window.setTimeout(swap, opts.interval);
  };

  const setVisible = (next: boolean) => {
    visible = next;
    schedule();
  };

  build();
  if (typeof IntersectionObserver === "undefined") {
    setVisible(true);
  } else {
    observer = new IntersectionObserver((entries) => {
      for (const entry of entries) setVisible(entry.isIntersecting);
    });
    observer.observe(el);
  }

  return {
    update(next) {
      const previous = opts;
      opts = { ...opts, ...next };
      // React passes a new array on every render: rebuild only when the words really change.
      if (currentList().join("\n") !== listKey) {
        build();
        schedule();
      } else if (opts.interval !== previous.interval) {
        schedule();
      }
      // duration is read at each swap.
    },
    destroy() {
      window.clearTimeout(timer);
      observer?.disconnect();
      observer = null;
      el.replaceChildren(...originalNodes);
      if (originalStyle === null) el.removeAttribute("style");
      else el.setAttribute("style", originalStyle);
      spans = [];
    },
  };
}
```

Two files that become yours: the engine, written without React, and a thin component around it. No package to install. The component is marked use client, so it sits inside a server component as it is.

Add it with the shadcn CLI
In a project set up for shadcn/ui, one command writes both files. Without it, copy them by hand in the two steps below.
Terminal
```
npx shadcn@latest add https://foundry44.dev/r/word-loop.json
```
Or add the engine by hand
Save it as lib/word-loop-core.ts. It has no dependencies and does nothing on the server.
TypeScript

And the component

Save it as components/ui/word-loop.tsx. It creates the effect on mount, passes every prop change to it live, and cleans up on unmount.

React

// Copyright (c) 2026 Foundry44 · MIT License (SPDX-License-Identifier: MIT)
// Generated by scripts/generate.mjs. Do not edit: change the core component instead.
"use client";
import { useEffect, useRef, type ComponentPropsWithoutRef } from "react";
import { wordLoop, type WordLoopOptions, type WordLoopInstance } from "@/lib/word-loop-core";

export interface WordLoopProps extends WordLoopOptions, Omit<ComponentPropsWithoutRef<"span">, keyof WordLoopOptions> {}

export function WordLoop({ words, interval, duration, style, ...props }: WordLoopProps) {
  const ref = useRef<HTMLElementTagNameMap["span"]>(null);
  const instance = useRef<WordLoopInstance | null>(null);

  useEffect(() => {
    if (!ref.current) return;
    instance.current = wordLoop(ref.current);
    return () => {
      instance.current?.destroy();
      instance.current = null;
    };
  }, []);

  // Runs right after creation, then on every option change.
  useEffect(() => {
    instance.current?.update(definedOnly({ words, interval, duration }));
  }, [words, interval, duration]);

  return <span ref={ref} style={style} {...props} />;
}

function definedOnly<T extends object>(o: T): T {
  return Object.fromEntries(Object.entries(o).filter(([, v]) => v !== undefined)) as T;
}

Or install the package
It is also on npm, in @foundry44/react with the other free components. Import it from there instead of @/components/ui.
Terminal
```
npm install @foundry44/react
```
React
```
import { WordLoop } from "@foundry44/react";
```

Use it

Every prop is optional: with none, you get the effect as the preview shows it.

React

import { WordLoop } from "@/components/ui/word-loop";

export function Example() {
  return (
    <WordLoop
      words={[]}
      interval={2500}
      duration={600}
    >
      {/* your content */}
    </WordLoop>
  );
}

Props

Prop	Default	What it is
words	[]	The words to cycle through, as an array or a comma-separated string. Defaults to the element's text, split on commas.
interval	2500	Time in ms each word stays before the next one replaces it.
duration	600	Time in ms for one swap.

Avoid the pitfalls
- It follows prefers-reduced-motion: under reduced motion the effect settles at once.
- The element keeps the width of the longest word: in the middle of a sentence, shorter words leave a gap after them. The effect reads best at the end of a line.
- Before the script runs, the element shows its own text. Writing the words there, separated by commas, gives a readable fallback.
- In React, pass the words as words, not as children: the element's content is rebuilt.
- Screen readers hear the whole list once, separated by commas, not each swap.

One file, readable, no dependencies and no build step. It sets itself up on every element marked data-f44="word-loop", in plain HTML, WordPress, Framer embeds or any framework.

Load the script

Download it, put it next to your page and load it once, anywhere in the page.

HTML

<script src="word-loop.js" defer></script>

Download word-loop.js Script, demo and photos (.zip)

The file

JavaScript

/*!
 * Foundry44 · Word Loop — https://foundry44.dev/components/word-loop
 * One word in a sentence cycles through alternatives with a vertical swap.
 * Copyright (c) 2026 Foundry44 · MIT License (SPDX-License-Identifier: MIT)
 *
 * Usage: load this file, then add data-f44="word-loop" to any element.
 * Optional attributes (defaults shown):
 *   data-f44-words="[]"
 *   data-f44-interval="2500"
 *   data-f44-duration="600"
 * Manual: const instance = Foundry44.wordLoop(element, { words: [], interval: 2500, duration: 600 });
 *         instance.destroy();
 * Re-scan the page after adding elements dynamically: Foundry44.init();
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */
(function () {
  "use strict";

  /**
   * Foundry44 — word-loop
   * One word in a sentence cycles through a list of alternatives. The current
   * word slides up and out behind an invisible edge while the next one rises
   * from below. The element keeps the width of the longest word, so the rest of
   * the sentence never shifts. The loop pauses while the element is offscreen.
   *
   * Self-contained: no imports, so this file can be copied as-is.
   */
  const wordLoopDefaults = {
    words: [],
    interval: 2500,
    duration: 600,
  };
  const EASE_OUT = "cubic-bezier(0.23, 1, 0.32, 1)";
  // Clips the top and bottom just outside the line, so descenders survive a tight line-height;
  // the sides are extended so italic overhangs are never cut.
  const MASK_CLIP = "inset(-0.08em -0.25em)";
  // Well past 100%: with a tight line-height, descenders and ascenders overflow the line box,
  // and a hidden word must clear the mask with them.
  const BELOW = "translateY(130%)";
  const ABOVE = "translateY(-130%)";
  const toList = (words) =>
    (typeof words === "string" ? words.split(",") : words).map((word) => word.trim()).filter(Boolean);
  function wordLoop(el, options = {}) {
    var _a, _b;
    let opts = { ...wordLoopDefaults, ...options };
    if (typeof window === "undefined") return { update() {}, destroy() {} };
    // Reduced motion keeps the rotation but drops the movement: words crossfade in place.
    const reduced =
      ((_a = window.matchMedia) === null || _a === void 0
        ? void 0
        : _a.call(window, "(prefers-reduced-motion: reduce)").matches) === true;
    const property = reduced ? "opacity" : "transform";
    const enterValue = reduced ? "0" : BELOW;
    const exitValue = reduced ? "0" : ABOVE;
    const shownValue = reduced ? "1" : "none";
    const originalStyle = el.getAttribute("style");
    // The original nodes are put back as-is on destroy() (frameworks keep references to them).
    const originalNodes = Array.from(el.childNodes);
    const textWords = toList((_b = el.textContent) !== null && _b !== void 0 ? _b : "");
    const currentList = () => {
      const list = toList(opts.words);
      return list.length ? list : textWords;
    };
    let spans = [];
    let listKey = "";
    let index = 0;
    let timer = 0;
    let visible = false;
    let observer = null;
    // Every word sits in the same grid cell, so the element takes the width of the
    // longest one and swapping never reflows the sentence around it.
    el.style.display = "inline-grid";
    el.style.justifyItems = "start";
    el.style.clipPath = MASK_CLIP;
    const build = () => {
      const list = currentList();
      listKey = list.join("\n");
      index = 0;
      el.replaceChildren();
      // Screen readers get the whole list once instead of hearing every swap.
      const label = document.createElement("span");
      label.textContent = list.join(", ");
      label.style.cssText =
        "position:absolute;width:1px;height:1px;overflow:hidden;clip-path:inset(50%);white-space:nowrap";
      el.appendChild(label);
      spans = list.map((word, i) => {
        const span = document.createElement("span");
        span.textContent = word;
        span.setAttribute("aria-hidden", "true");
        span.style.gridArea = "1 / 1";
        span.style.whiteSpace = "nowrap";
        span.style.setProperty(property, i === 0 ? shownValue : enterValue);
        el.appendChild(span);
        return span;
      });
    };
    const swap = () => {
      const from = spans[index];
      index = (index + 1) % spans.length;
      const to = spans[index];
      if (!from || !to) return;
      const transition = `${property} ${opts.duration}ms ${EASE_OUT}`;
      from.style.transition = transition;
      from.style.setProperty(property, exitValue);
      // Jump the incoming word below the edge first, so it always rises from the bottom.
      to.style.transition = "none";
      to.style.setProperty(property, enterValue);
      void to.offsetHeight;
      to.style.transition = transition;
      to.style.setProperty(property, shownValue);
      schedule();
    };
    const schedule = () => {
      window.clearTimeout(timer);
      timer = 0;
      if (visible && spans.length > 1) timer = window.setTimeout(swap, opts.interval);
    };
    const setVisible = (next) => {
      visible = next;
      schedule();
    };
    build();
    if (typeof IntersectionObserver === "undefined") {
      setVisible(true);
    } else {
      observer = new IntersectionObserver((entries) => {
        for (const entry of entries) setVisible(entry.isIntersecting);
      });
      observer.observe(el);
    }
    return {
      update(next) {
        const previous = opts;
        opts = { ...opts, ...next };
        // React passes a new array on every render: rebuild only when the words really change.
        if (currentList().join("\n") !== listKey) {
          build();
          schedule();
        } else if (opts.interval !== previous.interval) {
          schedule();
        }
        // duration is read at each swap.
      },
      destroy() {
        window.clearTimeout(timer);
        observer === null || observer === void 0 ? void 0 : observer.disconnect();
        observer = null;
        el.replaceChildren(...originalNodes);
        if (originalStyle === null) el.removeAttribute("style");
        else el.setAttribute("style", originalStyle);
        spans = [];
      },
    };
  }

  function parse(value) {
    if (value === "true") return true;
    if (value === "false") return false;
    var n = Number(value);
    return value !== "" && !isNaN(n) ? n : value;
  }

  function init() {
    document.querySelectorAll('[data-f44="word-loop"]').forEach(function (el) {
      if (el.__f44) return;
      var options = {};
      [
        ["words", "data-f44-words"],
        ["interval", "data-f44-interval"],
        ["duration", "data-f44-duration"],
      ].forEach(function (pair) {
        var value = el.getAttribute(pair[1]);
        if (value !== null) options[pair[0]] = parse(value);
      });
      el.__f44 = wordLoop(el, options);
    });
  }

  var Foundry44 = (window.Foundry44 = window.Foundry44 || {});
  Foundry44.wordLoop = wordLoop;
  Foundry44._inits = Foundry44._inits || [];
  Foundry44._inits.push(init);
  Foundry44.init = function () {
    Foundry44._inits.forEach(function (fn) {
      fn();
    });
  };

  if (document.readyState === "loading") document.addEventListener("DOMContentLoaded", init);
  else init();
})();

Mark your element

Add data-f44="word-loop". Each setting is an attribute on the same element, and an attribute always wins over the default.

HTML

<div data-f44="word-loop" data-f44-words="[]">
  <!-- your content -->
</div>

Settings

Attribute	Default	What it is
data-f44-words	[]	The words to cycle through, as an array or a comma-separated string. Defaults to the element's text, split on commas.
data-f44-interval	2500	Time in ms each word stays before the next one replaces it.
data-f44-duration	600	Time in ms for one swap.

Drive it from JavaScript

When the element arrives after the page has loaded, or when the settings come from your code.

JavaScript

// an element without data-f44, or the script would set it up twice
const element = document.querySelector(".my-element");
const instance = Foundry44.wordLoop(element, { words: [], interval: 2500 });

instance.update({ words: [] }); // any option, live
instance.destroy(); // listeners and observers gone, inline styles restored

// elements added after the page loaded
Foundry44.init();

Avoid the pitfalls
- It follows prefers-reduced-motion: under reduced motion the effect settles at once.
- The element keeps the width of the longest word: in the middle of a sentence, shorter words leave a gap after them. The effect reads best at the end of a line.
- Before the script runs, the element shows its own text. Writing the words there, separated by commas, gives a readable fallback.
- In React, pass the words as words, not as children: the element's content is rebuilt.
- Screen readers hear the whole list once, separated by commas, not each swap.

For a site builder: Webflow, WordPress, Shopify, Framer, or any site that accepts HTML. One block carries the whole script; paste it, then mark an element.

Paste the embed
Paste it where your builder takes custom HTML: an embed or code block on the page, or the site's footer code to use the effect on every page.
Not tested or supported on each platform. Many builders run scripts only on the published site or in preview. If the effect does not start, paste the block into your AI assistant and name your builder.

Mark the element

Give the element the attribute data-f44 with the value word-loop. Most builders have a field for custom attributes; otherwise, add it to the element's HTML.

Settings

Every setting is an attribute too, on the same element. Leave one out and the default applies.

Attribute	Default	What it is
data-f44-words	[]	The words to cycle through, as an array or a comma-separated string. Defaults to the element's text, split on commas.
data-f44-interval	2500	Time in ms each word stays before the next one replaces it.
data-f44-duration	600	Time in ms for one swap.

Avoid the pitfalls
- It follows prefers-reduced-motion: under reduced motion the effect settles at once.
- The element keeps the width of the longest word: in the middle of a sentence, shorter words leave a gap after them. The effect reads best at the end of a line.
- Before the script runs, the element shows its own text. Writing the words there, separated by commas, gives a readable fallback.
- In React, pass the words as words, not as children: the element's content is rebuilt.
- Screen readers hear the whole list once, separated by commas, not each swap.

Settings

What it does

Documentation

Copy the prompt

Ask for it

Add it with the shadcn CLI

Or add the engine by hand

And the component

Or install the package

Use it

Avoid the pitfalls

Load the script

Mark your element

Drive it from JavaScript

Avoid the pitfalls

Paste the embed

Mark the element

Avoid the pitfalls