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<html lang=en>

<head>

  <meta charset=UTF-8>

  <meta name=viewport content="width=device-width,initial-scale=1">

  <title>ondragenter — vs dragover &amp; dragleave</title>

  <style>body{font-family:system-ui,sans-serif;margin:0;padding:1.5rem;background:#f8fafc;color:#334155;line-height:1.7}h1{margin:0 0 .75rem;font-size:1.25rem;color:#0f172a}.drag-box{display:inline-block;padding:1rem 1.25rem;border:2px dashed #cbd5e1;border-radius:8px;background:#fff;cursor:grab;user-select:none;max-width:420px}.drag-box:active{cursor:grabbing}.drop-zone{margin-top:1rem;padding:1.25rem;border:2px dashed #94a3b8;border-radius:8px;background:#f1f5f9;max-width:420px;min-height:3rem}ul{margin:1rem 0 0;padding-left:1.25rem;font-size:.8125rem;max-width:420px}li{margin-bottom:.35rem}.enter{color:#15803d;font-weight:600}.over{color:#1d4ed8;font-weight:600}.leave{color:#b45309;font-weight:600}.drop{color:#7c3aed;font-weight:600}</style>

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<body>

  <h1>dragenter vs dragover vs dragleave</h1>

  <p>Drag the box into and out of the drop zone. dragover fires repeatedly; dragenter and dragleave fire on boundary changes.</p>

  <div class=drag-box draggable=true>Drag me into the zone.</div>

  <div class=drop-zone id=target>Drop target</div>

  <ul id=log></ul>



  <script>var target=document.getElementById("target"),log=document.getElementById("log"),overCount=0,overLine=null;function add(e,t){var n=document.createElement("li");t&&(n.className=t),n.textContent=e,log.appendChild(n),log.children.length>14&&log.removeChild(log.firstChild)}target.addEventListener("dragenter",(function(){add("dragenter (target, boundary entered)","enter")})),target.addEventListener("dragover",(function(e){e.preventDefault(),overCount+=1,overLine||((overLine=document.createElement("li")).className="over",log.appendChild(overLine)),overLine.textContent="dragover (target, "+overCount+" times while hovering)"})),target.addEventListener("dragleave",(function(){overCount=0,overLine=null,add("dragleave (target, boundary left)","leave")})),target.addEventListener("drop",(function(e){e.preventDefault(),add("drop (target, item released)","drop")}))</script>

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HTML ondragenter Attribute — dragenter vs dragover vs dragleave
