鍦℉TML5涓紝鍙互浣跨敤鍐呯疆鐨勮〃鍗曢獙璇佸睘鎬у拰鏂规硶鏉ヨ繘琛岄獙璇侊紝鑰宱nblur浜嬩欢鍙互鐢ㄦ潵瑙﹀彂楠岃瘉銆備緥濡傦紝鍦ㄤ竴涓猧nput鍏冪礌涓缃畆equired灞炴€э紝褰撶敤鎴风寮€璇ヨ緭鍏ユ鏃讹紝濡傛灉杈撳叆妗嗕负绌猴紝鍒欎細瑙﹀彂楠岃瘉銆?/p>

绀轰緥浠ｇ爜锛?/p>

<form>
  <input type="text" id="username" onblur="checkUsername()" required>
  <input type="submit" value="鎻愪氦">
</form>

<script>
function checkUsername() {
  var username = document.getElementById('username').value;
  if (username === "") {
    alert("鐢ㄦ埛鍚嶄笉鑳戒负绌?quot;);
  }
}
</script>

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鍥犳锛宱nblur浜嬩欢鍜孒TML5楠岃瘉鍙互鍏卞瓨骞朵竴璧蜂娇鐢ㄦ潵瀹炵幇鏇村ソ鐨勭敤鎴蜂綋楠屽拰鏁版嵁楠岃瘉銆?/p>