リンクを新しいタブで開く方法とdownload属性

<a href="https://example.com" target="_blank">Open in new tab</a>

<!-- target values:
  _blank  → new tab (or window)
  _self   → same tab (default)
  _parent → parent frame
  _top    → full window (exits frames)
-->

<a href="https://example.com"
   target="_blank"
   rel="noopener noreferrer">
  Open Safely
</a>
<!-- noopener: prevents access to window.opener -->
<!-- noreferrer: also hides referrer header + implies noopener -->
<!-- Modern browsers add noopener by default, but always include it -->

<a href="https://example.com"
   target="_blank"
   rel="noopener noreferrer"
   aria-label="Visit Example (opens in new tab)">
  Visit Example
  <span aria-hidden="true">↗</span>
</a>
<!-- aria-label covers screen reader announcement
     The arrow icon gives visual users a hint -->

<a href="/reports/q4-report.pdf" download>
  Download Q4 Report
</a>

<!-- Optionally specify the filename: -->
<a href="/api/export" download="my-data-2025.csv">
  Export CSV
</a>

<a href="data:text/plain;charset=utf-8,Hello%20World!"
   download="hello.txt">
  Download Text File
</a>
<!-- Generates a .txt file from inline data -->
<!-- Useful for generating small files client-side without a server -->

// If you must open a new window programmatically:
const win = window.open('https://example.com', '_blank', 'noopener,noreferrer');
// noopener via window.open requires the features string
// Not via rel on window.open

<a href="/destination" ping="/analytics/track">
  Track this click
</a>
<!-- Browser sends POST to /analytics/track when link is clicked -->
<!-- Rarely used — blocked by many browsers -->
<!-- Most analytics use JavaScript instead -->

<a href="/report.pdf" type="application/pdf">
  Download PDF Report
</a>
<a href="/data.json" type="application/json">
  JSON Data
</a>
<!-- Informational hint only — browser does not enforce it -->