你可以使用this.innerHTML。

<textarea name="message" rows =" 10" cols =" 100" onfocus="this。innerHTML= " ">在这里输入您的消息…textarea > < /

当文本区域被聚焦时，它基本上会使文本区域的innerHTML成为空字符串。

几点注意事项和澄清:

placeholder='' inserts your text, but it is greyed out (in a tool-tip style format) and the moment the field is clicked, your text is replaced by an empty text field. value='' is not a <textarea> attribute, and only works for <input> tags, ie, <input type='text'>, etc. I don't know why the creators of HTML5 decided not to incorporate that, but that's the way it is for now. The best method for inserting text into <textarea> elements has been outlined correctly here as: <textarea> Desired text to be inserted into the field upon page load </textarea> When the user clicks the field, they can edit the text and it remains in the field (unlike placeholder=''). Note: If you insert text between the <textarea> and </textarea> tags, you cannot use placeholder='' as it will be overwritten by your inserted text.

下面是我的jsFiddle示例。这很好:

<textarea name='awesome'>Default value</textarea>

同样，这对我来说也很有效:

<textarea class="form-control" rows="3" name="msg" placeholder="Your message here." onfocus='this.select()'>
<?php if (isset($_POST['encode'])) { echo htmlspecialchars($_POST['msg']);} ?>
</textarea>

在这种情况下，$_POST['encode']来自:

<input class="input_bottom btn btn-default" type="submit" name="encode" value="Encode">

PHP代码被插入到和标记之间。

占位符不能为文本区域设置默认值。你可以使用

<textarea rows="10" cols="55" name="description"> /*Enter default value here to display content</textarea>

如果您将它用于数据库连接，则它是标记。如果使用php以外的其他语言，则可以使用不同的语法。对于php:

例如:

<textarea rows="10" cols="55" name="description" required><?php echo $description; ?></textarea>

Required命令最大限度地减少了使用php检查空字段所需的工作。

你可以使用this.innerHTML。

<textarea name="message" rows =" 10" cols =" 100" onfocus="this。innerHTML= " ">在这里输入您的消息…textarea > < /

当文本区域被聚焦时，它基本上会使文本区域的innerHTML成为空字符串。