还有另一个关于这个的帖子,我试过了。但有一个问题:如果你删除内容,文本区域不会缩小。我找不到任何方法将其缩小到正确的大小- clientHeight值返回为文本区域的完整大小,而不是它的内容。

该页面的代码如下:

function FitToContent(id, maxHeight)
{
   var text = id && id.style ? id : document.getElementById(id);
   if ( !text )
      return;

   var adjustedHeight = text.clientHeight;
   if ( !maxHeight || maxHeight > adjustedHeight )
   {
      adjustedHeight = Math.max(text.scrollHeight, adjustedHeight);
      if ( maxHeight )
         adjustedHeight = Math.min(maxHeight, adjustedHeight);
      if ( adjustedHeight > text.clientHeight )
         text.style.height = adjustedHeight + "px";
   }
}

window.onload = function() {
    document.getElementById("ta").onkeyup = function() {
      FitToContent( this, 500 )
    };
}

当前回答

如果scrollHeight可以信任,那么:

textarea.onkeyup=function() {
  this.style.height='';
  this.rows=this.value.split('\n').length;
  this.style.height=this.scrollHeight+'px';
}

其他回答

我发现最好的方法是:

$("textarea.auto-grow").each( function(){
    $(this).keyup(function(){
        $(this).height( $(this)[0].scrollHeight - Number( $(this).css("font-size").replace("px", "") ) );
    });
});

其他方法有一个字体大小的错误。

这就是为什么这是最好的。

稍微更正一下。完美演绎歌剧

  $('textarea').bind('keyup keypress', function() {
      $(this).height('');
      var brCount = this.value.split('\n').length;
      this.rows = brCount+1; //++ To remove twitching
      var areaH = this.scrollHeight,
          lineHeight = $(this).css('line-height').replace('px',''),
          calcRows = Math.floor(areaH/lineHeight);
      this.rows = calcRows;
  });

React的一个示例实现:

const { useLayoutEffect, useState, useRef } = React; const TextArea = () => { const ref = useRef(); const [value, setValue] = useState('Some initial text that both wraps and uses\nnew\nlines'); // This only tracks the auto-sized height so we can tell if the user has manually resized const autoHeight = useRef(); useLayoutEffect(() => { if (!ref.current) { return; } if ( autoHeight.current !== undefined && ref.current.style.height !== autoHeight.current ) { // don't auto size if the user has manually changed the height return; } ref.current.style.height = "auto"; ref.current.style.overflow = "hidden"; const next = `${ref.current.scrollHeight}px`; ref.current.style.height = next; autoHeight.current = next; ref.current.style.overflow = "auto"; }, [value, ref, autoHeight]); return ( <textarea ref={ref} style={{ resize: 'vertical', minHeight: '1em', }} value={value} onChange={event => setValue(event.target.value)} /> ); } ReactDOM.render(<TextArea />, document.getElementById('app')) <script src="https://cdnjs.cloudflare.com/ajax/libs/react/17.0.1/umd/react.production.min.js"></script> <script src="https://cdnjs.cloudflare.com/ajax/libs/react-dom/17.0.1/umd/react-dom.production.min.js"></script> <div id="app"></div>

这是一种基于行的方法,允许您为文本区域设置最大行数,之后文本区域将显示滚动条。除了以rows属性的形式调整它的高度之外,它还会在键入或执行剪切和粘贴之类的操作时自动扩展它的宽度。

如果文本区域没有任何内容,只有一个占位符,它将根据占位符文本调整其宽度和高度。

这个版本的一个缺点是,它将继续无限增加它的宽度基于文本宽度。因此,你需要为文本区域设置一个max-width值。简单的max-width: 100%;也会有效果。这个宽度扩展特性主要基于type="text"的输入字段。你可以在这个答案中了解更多。

const textarea = document.querySelector('textarea'); setTextareaWidthHeight(textarea); textarea.addEventListener('input', setTextareaWidthHeight.bind(this, textarea)); function getInputWidth(element) { const text = element.value || element.placeholder; const elementStyle = window.getComputedStyle(element); const fontProperty = elementStyle.font; const horizontalBorder = parseFloat(elementStyle.borderLeftWidth) + parseFloat(elementStyle.borderRightWidth); const horizontalPadding = parseFloat(elementStyle.paddingLeft) + parseFloat(elementStyle.paddingRight); const canvas = document.createElement('canvas'); const context = canvas.getContext('2d'); context.font = fontProperty; const textWidth = context.measureText(text).width; const totalWidth = horizontalBorder + horizontalPadding + textWidth + "px"; return totalWidth; } function setTextareaWidthHeight(element) { // store minimum and maximum rows attribute value that should be imposed const minRows = 1; const maxRows = 5; // store initial inline overflow property value in a variable for later reverting to original condition const initialInlineOverflowY = element.style.overflowY; // change overflow-y property value to hidden to overcome inconsistent width differences caused by any scrollbar width element.style.overflowY = 'hidden'; const totalWidth = getInputWidth(element); element.style.width = totalWidth; let rows = minRows; element.setAttribute("rows", rows); while (rows <= maxRows && element.scrollHeight !== element.clientHeight) { element.setAttribute("rows", rows); rows++; } // change overflow to its original condition if (initialInlineOverflowY) { element.style.overflowY = initialInlineOverflowY; } else { element.style.removeProperty("overflow-y"); } } textarea { max-width: 100%; } <textarea placeholder="Lorem ipsum dolor sit amet"></textarea>

我不知道是否有人提到这种方式,但在某些情况下,可以用rows属性调整高度

textarea.setAttribute('rows',breaks);

Demo