我尝试了一些方法,但没有一个奏效。有人知道绕过这个的妙招吗?

<textarea placeholder='This is a line \n this should be a new line'></textarea>

<textarea placeholder='This is a line     
should this be a new line?'></textarea> <!-- this works in chrome apparently -->

更新:它不工作在chrome。它只是textarea的宽度。

参见:http://jsfiddle.net/pdXRx/


当前回答

我喜欢Jason Gennaro和Denis Golomazov的作品,但我想要一些在全球范围内更有用的东西。我已经修改了这个概念,这样它就可以添加到任何页面而不受影响。

http://jsfiddle.net/pdXRx/297/

<h1>Demo: 5 different textarea placeholder behaviors from a single JS</h1>

<h2>Modified behaviors</h2>

<!-- To get simulated placeholder with New Lines behavior,
     add the placeholdernl attribute -->

<textarea placeholdernl>    (click me to demo)
Johnny S. Fiddle
248 Fake St.
Atlanta, GA 30134</textarea>

<textarea placeholder='Address' placeholdernl>    (click me to demo)
Johnny S. Fiddle
248 Fake St.
Atlanta, GA 30134</textarea>

<h2>Standard behaviors</h2>

<textarea placeholder='Address'>    (delete me to demo)
Johnny S. Fiddle
248 Fake St.
Atlanta, GA 30134</textarea>

<textarea>    (delete me to demo)
Johnny S. Fiddle
248 Fake St.
Atlanta, GA 30134</textarea>

<textarea placeholder='Address'></textarea>

javascript非常简单

<script>
(function($){
var handleFocus = function(){
    var $this = $(this);
    if($this.val() === $this.attr('placeholdernl')){
        $this.attr('value', '');
        $this.css('color', '');
    }
};

var handleBlur = function(){
    var $this = $(this);
    if($this.val() == ''){
        $this.attr('value', $this.attr('placeholdernl'))
        $this.css('color', 'gray');
    }    
};

$('textarea[placeholdernl]').each(function(){
    var $this = $(this),
        value = $this.attr('value'),
        placeholder = $this.attr('placeholder');
    $this.attr('placeholdernl', value ? value : placeholder);
    $this.attr('value', '');
    $this.focus(handleFocus).blur(handleBlur).trigger('blur');
});
})(jQuery);
</script>

其他回答

如果你在ASP中使用Razor。NET项目,你可以做下面的事情,这对很长的占位符值很有帮助:

@{ 
    string strPlaceholder = "Shipment Id to Update, Container Id to Update, New Tracking Number \r\n"
        + "Shipment Id to Update, Container Id to Update, New Tracking Number \r\n"
        + "Shipment Id to Update, Container Id to Update, New Tracking Number \r\n"
        + "\r\n"
        + "i.e. to update all containers with shipment Id 5803407, etner like this: \r\n"
        + "5803407, , 1Z20579A0322337062 \r\n"
        + "\r\n"
        + "or to update a specific container Id, enter like this: \r\n"
        + "5803407, 112546247, 1Z20579A0322337062 \r\n"
        ;
}
<textarea type="text" class="form-control" style="height:650px;" id="ShipmentList" name="ShipmentList" 
            placeholder="@strPlaceholder" required></textarea>

我不喜欢隐藏占位符当你聚焦文本区域。所以我做了一个构造函数占位符,看起来完全像内置占位符,也工作在其他浏览器比谷歌Chrome。它非常方便,因为你可以随时使用占位符函数,甚至不需要jQuery。

编辑:

它现在还能正确处理特殊情况,比如插入占位符。

var textarea = document.getElementById("textarea"); new Placeholder(textarea, "Line 1\nLine 2\nLine 3"); function Placeholder(el, placeholder) { if (el.value == "" || el.value == placeholder) { el.style.color = "gray"; el.value = placeholder; el._plc = true; el.className += " unselectable"; } function keyPress(e) { window.setTimeout(function() { var replaced = reverseStr(el.value).replace(reverseStr(placeholder), ""); if (el.value == "") { el.value = placeholder; el.style.color = "gray"; cursorToStart(el); el._plc = true; el.className += " unselectable"; } else if (el._plc && el.value.endsWith(placeholder) && replaced !== "") { el.value = reverseStr(replaced); el.style.color = "black"; el._plc = false; el.readOnly = false; el.className = el.className.replace("unselectable", ""); } else if (el._plc && el.readOnly) { var ch = String.fromCharCode(e.charCode); if (e.keyCode == 13) ch = "\n"; // ENTER else if (e.charCode == 0) return; // non-character keys el.value = ch; el.style.color = "black"; el._plc = false; el.readOnly = false; el.className = el.className.replace("unselectable", ""); } }, 10); } el.addEventListener("keypress", keyPress, false); el.addEventListener("paste", keyPress, false); el.addEventListener("cut", keyPress, false); el.addEventListener("mousedown", function() { if (el._plc) el.readOnly = true; }, false); el.addEventListener("mouseup", function() { el.readOnly = false; if (el._plc) cursorToStart(el); }, false); function cursorToStart(input) { if (input.createTextRange) { var part = input.createTextRange(); part.move("character", 0); part.select(); } else if (input.setSelectionRange){ input.setSelectionRange(0, 0); } input.focus(); } function reverseStr(str) { if (!str) return ""; return str.split("").reverse().join(""); } } textarea { border: 1px solid gray; padding: 3px 6px; font-family: Arial; font-size: 13px; transition: .2s; } textarea:hover, textarea:focus { border-color: #2277cc; } textarea:focus { box-shadow: inset 0 0 5px #85B7E9; } *.unselectable { -webkit-user-select: none; -webkit-touch-callout: none; -khtml-user-select: none; -moz-user-select: none; -ms-user-select: none; -o-user-select: none; } <textarea id="textarea"></textarea>

不要认为你可以这样做:http://www.w3.org/TR/html5/forms.html#the-placeholder-attribute

相关内容(重点我):

占位符属性表示一个简短的提示(一个单词或简短的提示) 短语),用于帮助用户在控件出现故障时输入数据 没有价值。方法的示例值或简要描述可以是提示 预期的格式。如果指定了属性,则该属性的值必须为 不包含U+000A换行(LF)或U+000D回车(CR) 字符。

旧的回答:

不,你不能在占位符属性中这样做。你甚至不能用html编码像&#13;&#10;在占位符中。

新回答:

现代浏览器为您提供了几种方法。请看这个JSFiddle:

http://jsfiddle.net/pdXRx/5/

您可以做的是将文本作为值添加,它尊重换行符\n。

$('textarea').attr('value', 'This is a line \nthis should be a new line');

然后你可以在焦点上删除它,然后在模糊上应用它(如果为空)。就像这样

var placeholder = 'This is a line \nthis should be a new line';
$('textarea').attr('value', placeholder);

$('textarea').focus(function(){
    if($(this).val() === placeholder){
        $(this).attr('value', '');
    }
});

$('textarea').blur(function(){
    if($(this).val() ===''){
        $(this).attr('value', placeholder);
    }    
});

例如:http://jsfiddle.net/airandfingers/pdXRx/247/

不是纯粹的CSS,不干净,但做到了。