MOTION / 196
Seamless marquee
切れ目なく流れる繰り返し
同じ長さの内容を二組並べ、一組ぶんだけ動かして繰り返すと、継ぎ目を感じない流れになります。
見本の中を操作して変化を試してください。
実装コードを見る
<!doctype html><html lang="ja"><meta charset="utf-8"><meta name="viewport" content="width=device-width,initial-scale=1"><style>body{margin:0;min-height:300px}.sample{box-sizing:border-box;min-height:210px;width:100%;height:100%;display:grid;place-items:center;align-content:center;gap:18px;padding:24px;background:#efeee9;color:#202020;font-family:Arial,Meiryo,sans-serif;overflow:hidden}.sample *{box-sizing:border-box}.sample button{min-height:40px;border:1px solid #777;border-radius:999px;background:transparent;padding:9px 17px;font:12px Arial,Meiryo,sans-serif;color:inherit;cursor:pointer}.sample label{font-size:11px;display:grid;gap:8px;width:min(100%,220px)}.sample input{width:100%;accent-color:#222}.sample small{font-size:10px;line-height:1.6}.sample :focus-visible{outline:2px solid #222;outline-offset:4px}@media(prefers-reduced-motion:reduce){.sample *{animation:none!important;transition:none!important}}.marquee{width:100%;overflow:hidden;border-block:1px solid #bbb;padding-block:28px}.marquee-track{width:max-content;display:flex;animation:marquee-travel 10s linear infinite}.marquee-track span{display:block;white-space:pre;font-size:38px;font-weight:800;letter-spacing:-2px}.marquee.changed .marquee-track{animation-play-state:paused}@keyframes marquee-travel{to{transform:translateX(-50%)}}</style><div class="sample"><div class="marquee"><div class="marquee-track"><span>gooooooooood* </span><span aria-hidden="true">gooooooooood* </span></div></div><button data-toggle=".marquee" aria-pressed="false">停止／再開</button></div><script>const controller=(function controls(root){const abort=new AbortController();for(const input of root.querySelectorAll('[data-target]')){const update=()=>{const target=root.querySelector(input.dataset.target);if(input.dataset.attr)target.setAttribute(input.dataset.attr,input.value+(input.dataset.unit||''));else target.style.setProperty(input.dataset.prop,input.value+(input.dataset.unit||''));const output=input.closest('label')?.querySelector('output');if(output)output.textContent=input.value};input.addEventListener('input',update,{signal:abort.signal});update()}for(const button of root.querySelectorAll('[data-toggle]'))button.addEventListener('click',()=>{const target=root.querySelector(button.dataset.toggle),on=target.classList.toggle('changed');button.setAttribute('aria-pressed',String(on));},{signal:abort.signal});return {destroy(){abort.abort()},setAuto(){}}})(document);addEventListener('pagehide',()=>controller.destroy(),{once:true});</script></html>