<!DOCTYPE html><html><head><meta charset="utf-8"><title></title></head><body><form action="" method="post"><label id="label">郵編:<input type="text" name="text"value="" maxlength="6"><small>請輸入六位元字</small></label><input type="button" value="設定預設值" onclick="setValue()"></form><script type="text/javascript">function setValue(){var label = document.getElementById('label');var textbox = label.control;textbox.value='10010';}</script></body></html>
在HTML5中，可以在標籤內部放置一個表單元素，並且通過該標籤的control屬性來訪問該表單元素。
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