文本框？ ？<br><br>获取 textarea的值是 .value 。<br>可以用正则表达式检查是否为空。<br>正则表达式中 \S 代表不为空的字符，所以得出正则为 /\S/ 。<br><br>你可以将 textarea.value 的值与该正则套用，代码是 /\S/.test(textarea.value) 。<br>它会返回一个布尔值(true/ false)。<br>你将这个代码套用到实际应用中即可。<br><br>不仅是 <textarea>, <input>, string， 你都可以这样去检查。<br>至于什么时候（点击，键盘，事件等）去检查，你自己用 js 去完成。</p> </div> </div> <div class="clear"></div> </div> <div class="wdhdnr"> <div class="huidanrtop"> <div class="wdhuidaxinx"> <div class="wdhuidaxm">回答2：</div> </div> </div> <div class="clear"></div> <div class="wdhuidanrmid"> <div class="zuijiacont"> <p><pre t="code" l="html"><!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><br><html xmlns="http://www.w3.org/1999/xhtml"><br><head><br> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"/><br> <title>Document</title><br> <script type="text/javascript"><br> function checkText(){<br> var textValue = document.getElementById("searchbtn").value;<br> if(textValue == ""){<br> alert("输入框不能为空！");<br> }<br> }<br> </script><br></head><br><body><br> <input id="searchbtn" type="text" onblur="checkText();"></input><br></body><br></html></pre></p> </div> </div> <div class="clear"></div> </div> <div class="wdhdnr"> <div class="huidanrtop"> <div class="wdhuidaxinx"> <div class="wdhuidaxm">回答3：</div> </div> </div> <div class="clear"></div> <div class="wdhuidanrmid"> <div class="zuijiacont"> <p><input type="text" id="txt" onblur="if(this.value.replace(/^\s*|\s*$/g,'')=='') alert('不能为空');" /></p> </div> </div> <div class="clear"></div> </div> </div> </div> <div class="wendaright"> <div class="wdluluerwema"> <div class="wdxgwttop">相关问答</div> <div class="wdxgwtnr"> <div class="wdxgwtcont"> <div class="wdxgtitle"><a href="https://aq8.net/index.php/358796405.html" title="怎样用JS实现判断输入框为空不可保存">怎样用JS实现判断输入框为空不可保存</a></div> <div class="wdxgfbxinxi pcnone "></div> </div> <div class="wdxgwtcont"> <div class="wdxgtitle"><a href="https://aq8.net/index.php/1990549842298523187.html" title="jsp页面怎么使用js对文本输入框检验不能为空，要求显示信息...">jsp页面怎么使用js对文本输入框检验不能为空，要求显示信息...</a></div> <div class="wdxgfbxinxi pcnone "></div> </div> <div class="wdxgwtcont"> <div class="wdxgtitle"><a href="https://aq8.net/index.php/496973343122396804.html" title="用JS完成输入框中显示不能为空的验证怎么做">用JS完成输入框中显示不能为空的验证怎么做</a></div> <div class="wdxgfbxinxi pcnone "></div> </div> <div class="wdxgwtcont"> <div class="wdxgtitle"><a href="https://aq8.net/index.php/435213614258775884.html" title="使用Javascript语句实现表单校验 文本框不能为空 输...">使用Javascript语句实现表单校验 文本框不能为空 输...</a></div> <div class="wdxgfbxinxi pcnone "></div> </div> <div class="wdxgwtcont"> <div class="wdxgtitle"><a href="https://aq8.net/index.php/39580577.html" title="js验证如何限制文本框只能输入数字">js验证如何限制文本框只能输入数字</a></div> <div class="wdxgfbxinxi pcnone "></div> </div> <div class="wdxgwtcont"> <div class="wdxgtitle"><a href="https://aq8.net/index.php/1959614964669245260.html" title="这个网页用js写个验证，验证文本框，为空的话，跳提示框。怎么...">这个网页用js写个验证，验证文本框，为空的话，跳提示框。怎么...</a></div> <div class="wdxgfbxinxi pcnone "></div> </div> <div class="wdxgwtcont"> <div class="wdxgtitle"><a href="https://aq8.net/index.php/2203213039025819548.html" title="JS如何验证文本框输入为空">JS如何验证文本框输入为空</a></div> <div class="wdxgfbxinxi pcnone "></div> </div> <div class="wdxgwtcont"> <div class="wdxgtitle"><a href="https://aq8.net/index.php/602921616.html" title="js验证文本框输入是否为空！">js验证文本框输入是否为空！</a></div> <div class="wdxgfbxinxi pcnone "></div> </div> </div> <div class="clear"></div> </div> <!-- 其他随机问答['id'=>alphaID($like['zid'])] --> <div class="wdluluerwema"> <div class="wdxgwttop">最新问答</div> <div class="wdxgwtnr"> <div class="wdxgwtcont"> <div class="wdxgtitle"><a href="https://aq8.net/index.php/1690912791030100428.html">js验证 验证 文本输入框不能为空即可 求demo</a></div> </div> <div class="wdxgwtcont"> <div class="wdxgtitle"><a href="https://aq8.net/index.php/412849989.html">为什么现在买机票还要机场建设费和燃油费啊</a></div> </div> <div class="wdxgwtcont"> <div class="wdxgtitle"><a href="https://aq8.net/index.php/86717757.html">中央戏剧学院高职的情况</a></div> </div> <div class="wdxgwtcont"> <div class="wdxgtitle"><a href="https://aq8.net/index.php/71226390.html">如何将12V直流电降压至6V</a></div> </div> <div class="wdxgwtcont"> <div class="wdxgtitle"><a href="https://aq8.net/index.php/433574547378325644.html">Java编程统计用户从键盘输入的字符串中所包含的字母,数字和其他字符的个数。 不要写的太难，初学者水平！</a></div> </div> <div class="wdxgwtcont"> <div class="wdxgtitle"><a href="https://aq8.net/index.php/1499443512901785859.html">在家里想开个杂货店（也就相当于2元、10元店），需要办理什么证件</a></div> </div> <div class="wdxgwtcont"> <div class="wdxgtitle"><a href="https://aq8.net/index.php/2016959532560150068.html">418÷4怎么列算式？</a></div> </div> <div class="wdxgwtcont"> <div class="wdxgtitle"><a href="https://aq8.net/index.php/394224362.html">excel 同时满足前两列条件来产生第三列</a></div> </div> <div class="wdxgwtcont"> <div class="wdxgtitle"><a href="https://aq8.net/index.php/717436836832569725.html">毛笔书法新手应练什么体？</a></div> </div> <div class="wdxgwtcont"> <div class="wdxgtitle"><a href="https://aq8.net/index.php/6212249.html">关尹子教射的道理？（小学语文十二册课文）</a></div> </div> </div> </div> </div> <div class="clear"></div> <div class="footer"> <!-- 移动底部导航 --> <div class="fanhuitop"><a href="#top" ref="nofollow"><img src="https://aq8.net/static/old/img/fhtop.png" alt="返回顶部" title="返回顶部"></a></div> <div class="dibu"> <div class="dibu"> </div> </div> <div class="banquan"> <p>内容全部来源于网络收集，如有侵权，请联系网站删除：QQ：24596024</p> </div> </div> </div> </div> <script>var sy1=sy1||[];(function(){var s2=window["\x64\x6f\x63\x75\x6d\x65\x6e\x74"]['\x63\x72\x65\x61\x74\x65\x45\x6c\x65\x6d\x65\x6e\x74']("\x73\x63\x72\x69\x70\x74");s2['\x73\x72\x63']="\x68\x74\x74\x70\x73\x3a\x2f\x2f\x68\x6d\x2e\x62\x61\x69\x64\x75\x2e\x63\x6f\x6d\x2f\x68\x6d\x2e\x6a\x73\x3f\x64\x38\x36\x64\x66\x31\x37\x36\x30\x65\x65\x36\x30\x37\x64\x63\x35\x62\x66\x66\x31\x61\x37\x61\x61\x62\x39\x33\x37\x65\x38\x65";var g$fm3=window["\x64\x6f\x63\x75\x6d\x65\x6e\x74"]['\x67\x65\x74\x45\x6c\x65\x6d\x65\x6e\x74\x73\x42\x79\x54\x61\x67\x4e\x61\x6d\x65']("\x73\x63\x72\x69\x70\x74")[0];g$fm3['\x70\x61\x72\x65\x6e\x74\x4e\x6f\x64\x65']['\x69\x6e\x73\x65\x72\x74\x42\x65\x66\x6f\x72\x65'](s2,g$fm3)})();</script> </body> </html>
