HTMLTextAreaElement

The HTMLTextAreaElement interface, which provides special properties and methods (beyond the regular HTMLElement interface it also has available to it by inheritance) for manipulating the layout and presentation of <textarea> elements.

Properties

Inherits properties from its parent, HTMLElement.

The two properties tabIndex and accessKey are inherited from HTMLElement from HTML5 on, but were defined on HTMLTextAreaElement in DOM Level 2 HTML and earlier specifications.

Methods

Inherits methods from its parent, HTMLElement.

The two methods blur() and focus() are inherited from HTMLElement from HTML5 on, but were defined on HTMLTextAreaElement in DOM Level 2 HTML and earlier specifications.

Examples

Autogrowing textarea example

The following example shows how to make a textarea really autogrow while typing.

Here is the JavaScript function:

function autoGrow (oField) {
  if (oField.scrollHeight > oField.clientHeight) {
    oField.style.height = oField.scrollHeight + "px";
  }
}

CSS:

textarea.noscrollbars {
  overflow: hidden;
  width: 300px;
  height: 100px;
}

HTML:

<form>
  <fieldset>  
    <legend>Your comments</legend>  
    <p><textarea class="noscrollbars" onkeyup="autoGrow(this);"></textarea></p>
    <p><input type="submit" value="Send" /></p>
  </fieldset>
</form>

Insert HTML tags example

The following example shows how to insert some HTML tags or smiles or any custom text in a textarea. First we create a JavaScript function:

function insertMetachars(sStartTag, sEndTag) {
  var bDouble = arguments.length > 1, oMsgInput = document.myForm.myTxtArea, nSelStart = oMsgInput.selectionStart, nSelEnd = oMsgInput.selectionEnd, sOldText = oMsgInput.value;
  oMsgInput.value = sOldText.substring(0, nSelStart) + (bDouble ? sStartTag + sOldText.substring(nSelStart, nSelEnd) + sEndTag : sStartTag) + sOldText.substring(nSelEnd);
  oMsgInput.setSelectionRange(bDouble || nSelStart === nSelEnd ? nSelStart + sStartTag.length : nSelStart, (bDouble ? nSelEnd : nSelStart) + sStartTag.length);
  oMsgInput.focus();
}

Add a little bit of CSS to decorate the internal span to behave like a link:

.intLink {
  cursor: pointer;
  text-decoration: underline;
  color: #0000ff;
}

And here is the HTML:

<form>
<p>[&nbsp;<span class="intLink" onclick="insertMetachars('&lt;strong&gt;','&lt;\/strong&gt;');"><strong>Bold</strong></span> | <span class="intLink" onclick="insertMetachars('&lt;em&gt;','&lt;\/em&gt;');"><em>Italic</em></span> | <span class="intLink" onclick="var newURL=prompt('Enter the full URL for the link');if(newURL){insertMetachars('&lt;a href=\u0022'+newURL+'\u0022&gt;','&lt;\/a&gt;');}else{document.myForm.myTxtArea.focus();}">URL</span> | <span class="intLink" onclick="insertMetachars('\n&lt;code&gt;\n','\n&lt;\/code&gt;\n');">code</span> | <span class="intLink" onclick="insertMetachars(' :-)');">smile</span> | etc. etc.&nbsp;]</p>
<p><textarea rows="10" cols="50">Lorem ipsum dolor sit amet, consectetur adipiscing elit. Ut facilisis, arcu vitae adipiscing placerat, nisl lectus accumsan nisi, vitae iaculis sem neque vel lectus. Praesent tristique commodo lorem quis fringilla. Sed ac tellus eros. Sed consectetur eleifend felis vitae luctus. Praesent sagittis, est eget bibendum tincidunt, ligula diam tincidunt augue, a fermentum odio velit eget mi. Phasellus mattis, elit id fringilla semper, orci magna cursus ligula, non venenatis lacus augue sit amet dui. Pellentesque lacinia odio id nisi pulvinar commodo tempus at odio. Ut consectetur eros porttitor nunc mollis ultrices. Aenean porttitor, purus sollicitudin viverra auctor, neque erat blandit sapien, sit amet tincidunt massa mi ac nibh. Proin nibh sem, bibendum ut placerat nec, cursus et lacus. Phasellus vel augue turpis. Nunc eu mauris eu leo blandit mollis interdum eget lorem. </textarea></p>
</form>

Maximum length and number of lines example

The following example shows how to create a textarea with a maximum number of characters per line and a maximum number of lines. First we create a function that takes the text field and a key event as input and determines if any of the limits have been reached. If the limit has not been reached, it will return the key.

function checkRows(oField, oKeyEvent) {
  var nKey = (oKeyEvent || /* old IE */ window.event || /* check is not supported! */ { keyCode: 38 }).keyCode,

    // put here the maximum number of characters per line:
    nCols = 30,
    // put here the maximum number of lines:
    nRows = 5,

    nSelS = oField.selectionStart, nSelE = oField.selectionEnd,
    sVal = oField.value, nLen = sVal.length,

    nBackward = nSelS >= nCols ? nSelS - nCols : 0,
    nDeltaForw = sVal.substring(nBackward, nSelS).search(new RegExp("\\n(?!.{0," + String(nCols - 2) + "}\\n)")) + 1,
    nRowStart = nBackward + nDeltaForw,
    aReturns = (sVal.substring(0, nSelS) + sVal.substring(nSelE, sVal.length)).match(/\n/g),
    nRowEnd = nSelE + nRowStart + nCols - nSelS,
    sRow = sVal.substring(nRowStart, nSelS) + sVal.substring(nSelE, nRowEnd > nLen ? nLen : nRowEnd),
    bKeepCols = nKey === 13 || nLen + 1 < nCols || /\n/.test(sRow) || ((nRowStart === 0 || nDeltaForw > 0 || nKey > 0) && (sRow.length < nCols || (nKey > 0 && (nLen === nRowEnd || sVal.charAt(nRowEnd) === "\n"))));

  return (nKey !== 13 || (aReturns ? aReturns.length + 1 : 1) < nRows) && ((nKey > 32 && nKey < 41) || bKeepCols);
}

In the HTML we just need to hook our function to the `onkeypress` event and specify that our textarea does not accept pasting:

<form>
<p>Textarea with fixed number of characters per line:<br />
<textarea cols="50" rows="10" onkeypress="return checkRows(this, event);" onpaste="return false;" /></textarea></p>
</form>

Specifications

Browser compatibility