javascript - HTML 的最大长度</h1> <div id="body"><p>How to restrict the maximum number of characters that can be entered into an HTML <code><textarea></code>? I'm looking for a cross-browser solution.</p> </div> <</a></h1> <div class="ml12 aside-cta flex--item print:d-none sm:ml0 sm:mb12 sm:order-first sm:as-end"> <a href="https://stackoverflow.com/questions/ask" target="_blank" class="ws-nowrap s-btn s-btnprimary">问问题</a></div> </div> <div class="d-flex fw-wrap pb8 mb16 bb bc-black-075"> <div class="flex--item ws-nowrap mr16 mb8"> <span class="fc-light mr2">cmsherratt</span> </div> <div class="flex--item ws-nowrap mr16 mb8" title="2022-04-17 15:46:40Z"> <span class="fc-light mr2">问问题</span> <time itemprop="dateCreated" datetime="2008-09-04T11:59:41.237">2008-09-04T11:59:41.237</time> </div> <div class="flex--item ws-nowrap mb8" title="Viewed 6 times"> <span class="fc-light mr2"></span> 17969 次 </div> </div> <div id="mainbar" role="main" aria-label="question and answers"> <div class="question" data-questionid="4" data-position-on-page="0" data-score="763" id="question"> <div class="post-layout"> <div class="votecell post-layout--left"> <div 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title="show questions tagged 'cross-browser'" rel="tag">cross-browser</a><a href="/tags/textarea" class="post-tag js-gps-track" title="show questions tagged 'textarea'" rel="tag">textarea</a> </div> </div> </div> </div> <span class="d-none" itemprop="commentCount">4</span> </div> </div> <div class="js-zone-container zone-container-responsive"> <div id="dfp-isb" class="everyonelovesstackoverflow everyonelovesinline-sidebar mx-auto" style="min-height: auto; height: auto; display: none;"></div> <div class="js-report-ad-button-container mx-auto" style="width: 300px"></div> </div> <div id="answers"> <a name="tab-top"></a> <div id="answers-header"> <div class="answers-subheader d-flex ai-center mb8"> <div class="flex--item fl1"> <h2 class="mb0" data-answercount=""> 3 回答 <span style="display:none;" itemprop="answerCount">3</span> </h2> </div> </div> </div> <a name="7"></a> <div id="answer-7" class="answer js-answer accepted-answer" data-answerid="7" data-parentid="4" data-score="506" data-position-on-page="1" data-highest-scored="1" data-question-has-accepted-highest-score="1" itemprop="suggestedAnswer" itemscope="" itemtype="https://schema.org/Answer"> <div class="post-layout"> <div class="votecell post-layout--left"> <div class="js-voting-container d-flex jc-center fd-column ai-stretch gs4 fc-black-200" data-post-id="7"> <button class="js-vote-up-btn flex--item s-btn s-btnunset c-pointer " data-controller="s-tooltip" data-s-tooltip-placement="right" aria-pressed="false" aria-label="Up vote" data-selected-classes="fc-theme-primary" data-unselected-classes="" aria-describedby="--stacks-s-tooltip-dgvag2l3"> <svg aria-hidden="true" class="svg-icon iconArrowUpLg" width="36" height="36" viewBox="0 0 36 36"><path d="M2 25h32L18 9 2 25Z"></path></svg> </button><div id="--stacks-s-tooltip-dgvag2l3" class="s-popover s-popovertooltip pe-none" aria-hidden="true" role="tooltip">This answer is useful<div class="s-popover--arrow"></div></div> <div class="js-vote-count flex--item d-flex fd-column ai-center fc-black-500 fs-title" itemprop="upvoteCount" data-value="21"> 21 </div> <button class="js-vote-down-btn flex--item s-btn s-btnunset c-pointer " data-controller="s-tooltip" data-s-tooltip-placement="right" aria-pressed="false" aria-label="Down vote" data-selected-classes="fc-theme-primary" data-unselected-classes="" aria-describedby="--stacks-s-tooltip-gn8ppsfv"> <svg aria-hidden="true" class="svg-icon iconArrowDownLg" width="36" height="36" viewBox="0 0 36 36"><path d="M2 11h32L18 27 2 11Z"></path></svg> </button> </div> </div> <div class="answercell post-layout--right"> <div class="s-prose js-post-body" itemprop="text"> <p><code>TEXTAREA</code>标签没有标签那样的属性<code>MAXLENGTH</code>， <code>INPUT</code>至少在大多数标准浏览器中没有。限制可<em>输入</em><code>TEXTAREA</code>标签的字符数的一种非常简单有效的方法是：</p> <pre><code><textarea onKeyPress="return ( this.value.length < 50 );"></textarea> </code></pre> <p><strong>注意：</strong> <code>onKeyPress</code> , 将阻止任何按钮按下，<em>包括</em>退格键在内的<strong>任何按钮。</strong> <em></em></p> <p>这是因为布尔表达式将在添加新字符之前的字段长度与您想要的最大长度（本例中为 50，在此使用您自己的）进行比较，如果还有空间，则返回 true，<code>false</code>如果没有。从大多数事件中返回 false 会取消默认操作。因此如果当前长度已经是 50（或更多），则处理程序返回 false，<code>KeyPress</code>取消操作，并且不添加字符。</p> <p>美中不足的是可以粘贴到 a<code>TEXTAREA</code>中，这不会导致<code>KeyPress</code>事件触发，从而绕过此检查。Internet Explorer 5+ 包含一个<code>onPaste</code>事件，其处理程序可以包含检查。但是，请注意，您还必须考虑剪贴板中等待的字符数，以了解总数是否会超过限制。幸运的是，IE 还包含来自窗口对象的剪贴板对象。<a href="http://lists.evolt.org/archive/Week-of-Mon-20040315/156773.html" rel="nofollow noreferrer">1</a>因此：</p> <pre><code><textarea onKeyPress="return ( this.value.length < 50 );" onPaste="return (( this.value.length + window.clipboardData.getData('Text').length) < 50 );"></textarea> </code></pre> <p>同样，<code>onPaste</code>事件和<code>clipboardData</code>对象仅适用于 IE 5+。对于跨浏览器解决方案，您只需要使用<code>OnChange</code>or<code>OnBlur</code>处理程序来检查长度，并根据需要进行处理（静默截断值，通知用户等）。不幸的是，这并没有捕捉到正在发生的错误，只有当用户尝试离开该字段时，这并不那么友好。</p> <p><a href="http://lists.evolt.org/archive/Week-of-Mon-20040315/156773.html" rel="nofollow noreferrer">资源</a></p> <p>此外，这里还有另一种方法，包括可以包含在页面中的完成脚本：</p> <p><a href="http://cf-bill.blogspot.com/2005/05/textarea-maxlength-revisited.html" rel="nofollow noreferrer">http://cf-bill.blogspot.com/2005/05/textarea-maxlength-revisited.html</a></p> </div> <div class="mt24"> <div class="user-action-time" style="color:#999;text-align:right;">于 2008-09-04T12:02:01.073 回答</div> </div> </div> </div> </div><a name="7"></a> <div id="answer-7" class="answer js-answer accepted-answer" data-answerid="7" data-parentid="4" data-score="506" data-position-on-page="1" data-highest-scored="1" data-question-has-accepted-highest-score="1" itemprop="suggestedAnswer" itemscope="" itemtype="https://schema.org/Answer"> <div class="post-layout"> <div class="votecell post-layout--left"> <div class="js-voting-container d-flex jc-center fd-column ai-stretch gs4 fc-black-200" data-post-id="7"> <button class="js-vote-up-btn flex--item s-btn s-btnunset c-pointer " data-controller="s-tooltip" data-s-tooltip-placement="right" aria-pressed="false" aria-label="Up vote" data-selected-classes="fc-theme-primary" data-unselected-classes="" aria-describedby="--stacks-s-tooltip-dgvag2l3"> <svg aria-hidden="true" class="svg-icon iconArrowUpLg" width="36" height="36" viewBox="0 0 36 36"><path d="M2 25h32L18 9 2 25Z"></path></svg> </button><div id="--stacks-s-tooltip-dgvag2l3" class="s-popover s-popovertooltip pe-none" aria-hidden="true" role="tooltip">This answer is useful<div class="s-popover--arrow"></div></div> <div class="js-vote-count flex--item d-flex fd-column ai-center fc-black-500 fs-title" itemprop="upvoteCount" data-value="6"> 6 </div> <button class="js-vote-down-btn flex--item s-btn s-btnunset c-pointer " data-controller="s-tooltip" data-s-tooltip-placement="right" aria-pressed="false" aria-label="Down vote" data-selected-classes="fc-theme-primary" data-unselected-classes="" aria-describedby="--stacks-s-tooltip-gn8ppsfv"> <svg aria-hidden="true" class="svg-icon iconArrowDownLg" width="36" height="36" viewBox="0 0 36 36"><path d="M2 11h32L18 27 2 11Z"></path></svg> </button> </div> </div> <div class="answercell post-layout--right"> <div class="s-prose js-post-body" itemprop="text"> <p>HTML5 现在<a href="https://developer.mozilla.org/en/docs/Web/HTML/Element/textarea#attr-maxlength" rel="nofollow"><code>maxlength</code>允许<code><textarea></code></a>.</p> <p>除 IE <= 9 和 iOS Safari 8.4 外，所有浏览器都支持它。请参阅<a href="http://caniuse.com/#feat=maxlength" rel="nofollow">caniuse.com 上的支持表</a>。</p> </div> <div class="mt24"> <div class="user-action-time" style="color:#999;text-align:right;">于 2012-08-14T17:29:26.377 回答</div> </div> </div> </div> </div><a name="7"></a> <div id="answer-7" class="answer js-answer accepted-answer" data-answerid="7" data-parentid="4" data-score="506" data-position-on-page="1" data-highest-scored="1" data-question-has-accepted-highest-score="1" itemprop="suggestedAnswer" itemscope="" itemtype="https://schema.org/Answer"> <div class="post-layout"> <div class="votecell post-layout--left"> <div class="js-voting-container d-flex jc-center fd-column ai-stretch gs4 fc-black-200" data-post-id="7"> <button class="js-vote-up-btn flex--item s-btn s-btnunset c-pointer " data-controller="s-tooltip" data-s-tooltip-placement="right" aria-pressed="false" aria-label="Up vote" data-selected-classes="fc-theme-primary" data-unselected-classes="" aria-describedby="--stacks-s-tooltip-dgvag2l3"> <svg aria-hidden="true" class="svg-icon iconArrowUpLg" width="36" height="36" viewBox="0 0 36 36"><path d="M2 25h32L18 9 2 25Z"></path></svg> </button><div id="--stacks-s-tooltip-dgvag2l3" class="s-popover s-popovertooltip pe-none" aria-hidden="true" role="tooltip">This answer is useful<div class="s-popover--arrow"></div></div> <div class="js-vote-count flex--item d-flex fd-column ai-center fc-black-500 fs-title" itemprop="upvoteCount" data-value="-2"> -2 </div> <button class="js-vote-down-btn flex--item s-btn s-btnunset c-pointer " data-controller="s-tooltip" data-s-tooltip-placement="right" aria-pressed="false" aria-label="Down vote" data-selected-classes="fc-theme-primary" data-unselected-classes="" aria-describedby="--stacks-s-tooltip-gn8ppsfv"> <svg aria-hidden="true" class="svg-icon iconArrowDownLg" width="36" height="36" viewBox="0 0 36 36"><path d="M2 11h32L18 27 2 11Z"></path></svg> </button> </div> </div> <div class="answercell post-layout--right"> <div class="s-prose js-post-body" itemprop="text"> <pre><code>$(function(){ $("#id").keypress(function() { var maxlen = 100; if ($(this).val().length > maxlen) { return false; } }) }); </code></pre> <p>参考<a href="https://stackoverflow.com/questions/4459610/set-maxlength-in-html-textarea">在 Html Textarea 中设置 maxlength</a></p> </div> <div class="mt24"> <div class="user-action-time" style="color:#999;text-align:right;">于 2014-04-11T06:59:34.410 回答</div> </div> </div> </div> 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