<input type='text' id='num' name='tel' value='021jz.com.cn' onKeyUp="showLen(this);"><span id="span">已輸入XX位</span><script type="text/javascript">showLen(document.getElementById("num"));function showLen(obj){document.getElementById('span').innerHTML = '已輸入'+ (obj.value.length) +'個(gè)字符';}</script>JS判斷已輸入多(duō)少字符,提示用(yòng)戶信息