问题

我想要有任何输入（在这种情况下，我猜是元素），就像WhatsApp或Telegram一样。默认情况下，它应该是1行。但当一行文本溢出时，它应该变成2行文本框。当第二行也溢出时，它应该变成3行文本框。反之亦然。我不知道如何实现这一点。我最初的想法是计算输入文本字符，然后根据符号的数量更改行数。但后来我意识到这是一个坏主意，因为不同的字符具有不同的宽度。当字体是Arial时，字符串"wwwwwwwwww"比"iiiiiiiiii"更宽，但两个字符串都有10个字符。</p> <details> <summary>英文:</summary> <p>I'd like to have any input ( <textarea> element in this case I guess) like in Whatsapp or Telegram. It should be 1 line by default. But when a line is overflown with text it should become 2-line textarea. And when the second line is also overflown, it should become a 3-line textarea. And vice versa.<br /> I have no idea how to implement this. My first thought was to count input text characters and then change the lines depending on the amount of symbols. But then I realized it was a bad idea because different characters have different width. And a string "wwwwwwwwww" is wider than "iiiiiiiiii" when the font is Arial, but both strings have 10 characters.</p> </details> <h1 id="1">答案1</h1> <p><strong>得分</strong>: 0</p> <p>根据scrollHeight属性更改textarea元素的高度。以下是使用jQuery的示例。如果仅用于单个textarea输入，可以简化代码。</p> <pre tabindex="0" style="color:#f8f8f2;background-color:#272822;"><code><span style="display:flex;"><span><span style="color:#a6e22e">$</span>(<span style="color:#e6db74">"#divContainingAutoSizingTextareas"</span>).<span style="color:#a6e22e">on</span>(<span style="color:#e6db74">"keyup"</span>, <span style="color:#e6db74">"textarea:focus"</span>, <span style="color:#66d9ef">function</span> (<span style="color:#a6e22e">e</span>) { </span></span><span style="display:flex;"><span> <span style="color:#66d9ef">var</span> <span style="color:#a6e22e">textarea</span> <span style="color:#f92672">=</span> <span style="color:#a6e22e">$</span>(<span style="color:#e6db74">":focus"</span>); </span></span><span style="display:flex;"><span> <span style="color:#a6e22e">textarea</span>.<span style="color:#a6e22e">height</span>(<span style="color:#a6e22e">textarea</span>.<span style="color:#a6e22e">prop</span>(<span style="color:#e6db74">"scrollHeight"</span>) <span style="color:#f92672">-</span> <span style="color:#ae81ff">12</span>); </span></span><span style="display:flex;"><span>}) </span></span></code></pre> <p>以下是一个不使用jQuery的示例。重置高度的目的是在删除内容时使textarea缩小。+2的目的是调整可能导致不一致结果的任何样式 - 您可以轻松确定尺寸是否在一致调整，并相应地进行调整。</p> <pre tabindex="0" style="color:#f8f8f2;background-color:#272822;"><code><span style="display:flex;"><span>document.<span style="color:#a6e22e">getElementById</span>(<span style="color:#e6db74">"autoexpand"</span>).<span style="color:#a6e22e">addEventListener</span>(<span style="color:#e6db74">"keyup"</span>, <span style="color:#66d9ef">function</span> () { </span></span><span style="display:flex;"><span> <span style="color:#66d9ef">var</span> <span style="color:#a6e22e">textarea</span> <span style="color:#f92672">=</span> document.<span style="color:#a6e22e">getElementById</span>(<span style="color:#e6db74">"autoexpand"</span>); </span></span><span style="display:flex;"><span> <span style="color:#a6e22e">textarea</span>.<span style="color:#a6e22e">style</span>.<span style="color:#a6e22e">height</span> <span style="color:#f92672">=</span> <span style="color:#e6db74">"34px"</span>; </span></span><span style="display:flex;"><span> <span style="color:#a6e22e">textarea</span>.<span style="color:#a6e22e">style</span>.<span style="color:#a6e22e">height</span> <span style="color:#f92672">=</span> <span style="color:#a6e22e">textarea</span>.<span style="color:#a6e22e">scrollHeight</span> <span style="color:#f92672">+</span> <span style="color:#ae81ff">2</span> <span style="color:#f92672">+</span> <span style="color:#e6db74">"px"</span>; </span></span><span style="display:flex;"><span>}) </span></span></code></pre> <details> <summary>英文:</summary> <p>Change the height of the textarea element based on the scrollHeight property. Here is an example using jQuery. It could be simplified if used for a single textarea input.</p> <pre><code>$("#divContainingAutoSizingTextareas").on("keyup", "textarea:focus", function (e) { var textarea = $(":focus"); textarea.height(textarea.prop("scrollHeight") - 12); }) </code></pre> <p>Here is an example without jQuery. The purpose of resetting height is to cause the textarea to shrink when content is removed. The purpose of the + 2 is to adjust for any styling that may make inconsistent results -- you can easily determine if the sizing is adjusting consistently and adjust accordingly.</p> <pre><code>document.getElementById("autoexpand").addEventListener("keyup", function () { var textarea = document.getElementById("autoexpand"); textarea.style.height = "34px"; textarea.style.height = textarea.scrollHeight + 2 + "px"; }) </code></pre> </details> </p> </div> <div class="copyright-post betip" > <div class="be-nav-l"> <div class="be-nav-logo"> <div class="logo-site"> <div class="site-name-main"> <p class="site-description">通过集体智慧和协作来改善编程学习和解决问题的方式。致力于成为全球开发者共同参与的知识库，让每个人都能够通过互相帮助和分享经验来进步。</p> </div> </div> </div> </div> </div> <div class="clear"></div> <div class="turn-small"></div> <div class="sharing-box betip" data-aos="zoom-in"> <a class="be-btn-beshare be-btn-donate use-beshare-donate-btn" rel="external nofollow" data-hover="打赏"><div class="arrow-share"></div></a> <a class="be-btn-beshare 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