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  <title>onerror — one-liner</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}img{display:block;width:120px;height:80px;object-fit:contain;border-radius:8px;border:1px solid #e2e8f0;background:#f1f5f9;margin-bottom:.75rem}.hint{font-size:.8125rem;color:#64748b;max-width:420px}code{background:#e2e8f0;padding:.1rem .35rem;border-radius:4px}</style>

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  <h1>One-liner onerror</h1>

  <p>Common pattern for avatars and thumbnails:</p>

  <img src=/images/__missing-avatar__.webp alt="User avatar" onerror='this.onerror=null,this.src="/images/codetofun-logo.png"'>

  <p class=hint><code>this.onerror=null</code> prevents an infinite loop if the fallback also fails.</p>

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HTML onerror Attribute — One-liner fallback