js memantau peristiwa tetikus untuk mengawal bilangan rentetan input dalam kemahiran textarea_javascript

<table>

<tr>

<td width="150">短信内容：</td>

<td>

<textarea name="message" cols="96" rows="5" onKeyDown="textCounter(message,remLen,65);"

onKeyUp="textCounter(message,remLen,65);"></textarea>

<td>
</tr>

<tr><td></td>
<td>您还可以输入:<input name="remLen" type="text" value="65" size="5" readonly="readonly">个字符,每条短信最大允许输入<strong>65</strong>个字符</td>

</tr>

</table>

<script>
function textCounter(field, countfield, maxlimit) {
if (field.value.length > maxlimit)
field.value = field.value.substring(0, maxlimit);
else
countfield.value = maxlimit - field.value.length;
}
</script>