Javascript 文本框的字符限制
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Character Limit On Textbox
提问by slandau
<input id="post" type="text" style="width:400px;"/>
You know when you go to a site, start typing in a textbox, and all of a sudden, your keyboard stops typing stuff because you've reached the character limit?
您知道当您访问某个网站时，开始在文本框中输入内容时，突然间，您的键盘因为已达到字符数限制而停止输入内容吗？
How can I make that happen for this textbox for 140 chars?
我怎样才能为这个 140 个字符的文本框做到这一点？
回答by Town
回答by wesbos
Using the jQuery Limit plugin : http://jsfiddle.net/AqPQT/(Demo)
使用 jQuery 限制插件：http: //jsfiddle.net/AqPQT/（演示）
<script src="http://jquery-limit.googlecode.com/files/jquery.limit-1.2.source.js"></script>
<textarea ></textarea>
<span id="left" />
and
和
$('textarea').limit('140','#left');
see also: http://unwrongest.com/projects/limit/
另见：http: //unwrongest.com/projects/limit/
If you are looking for a sans-jquery solution, just use the maxlength attribute.
如果您正在寻找 sans-jquery 解决方案，只需使用 maxlength 属性。
<input type="text" maxlength="140" />
回答by Mani
Try this piece of code..
试试这段代码..
var limitCount;
function limitText(limitField, limitNum)
{
if (limitField.value.length > limitNum)
{
limitField.value = limitField.value.substring(0, limitNum);
}
else
{
if (limitField == '')
{
limitCount = limitNum - 0;
}
else
{
limitCount = limitNum - limitField.value.length;
}
}
if (limitCount == 0)
{
document.getElementById("comment").style.borderColor = "red";
}
else
{
document.getElementById("comment").style.borderColor = "";
}
}<input type="text" id="comment" name="comment" onkeyup="limitText(this,20);" onkeypress="limitText(this,20);" onkeydown="limitText(this,20);" />回答by albert
function limitChars(textid, limit, infodiv) {
var text = $('#'+textid).val();
var textlength = text.length;
if(textlength > limit) {
$('#' + infodiv).html('You cannot write more then '+limit+' characters!');
$('#'+textid).val(text.substr(0,limit));
return false;
}
else {
$('#' + infodiv).html('You have '+ (limit - textlength) +' characters left.');
return true;
}
}
// Bind the function to ready event of document.
$(function(){
$('#comment').keyup(function(){
limitChars('comment', 140, 'charlimitinfo');
})
});
