<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <HTML> <HEAD> <TITLE>计算文本框允许输入字符的百分比</TITLE> </HEAD> <BODY> <style type="text/css"> .progress{ width: 1px; height: 14px; color: white; font-size: 12px; overflow: hidden; background-color: navy; padding-left: 5px; } </style> <script type="text/JavaScript"> function textCounter(field,counter,maxlimit,linecounter) { var fieldWidth = parseInt(field.offsetWidth); var charcnt = field.value.length; // trim the extra text if (charcnt > maxlimit) { field.value = field.value.substring(0, maxlimit); } else { // progress bar percentage var percentage = parseInt(100 - (( maxlimit - charcnt) * 100)/maxlimit) ; document.getElementById(counter).style.width = parseInt((fieldWidth*percentage)/100)+"px"; document.getElementById(counter).innerHTML="已输: "+percentage+"%" // color correction on style from CCFFF -> CC0000 setcolor(document.getElementById(counter),percentage,"background-color"); } } function setcolor(obj,percentage,prop){ obj.style[prop] = "rgb(80%,"+(100-percentage)+"%,"+(100-percentage)+"%)"; } </script> <p>限制：120字节</P> <form> <textarea rows="5" cols="40" name="maxcharfield" id="maxcharfield" onKeyDown="textCounter(this,'progressbar1',120)" onKeyUp="textCounter(this,'progressbar1',120)" onFocus="textCounter(this,'progressbar1',120)" ></textarea><br /> <div id="progressbar1" class="progress"></div> <script>textCounter(document.getElementById("maxcharfield"),"progressbar1",120)</script> </form> </BODY> </HTML>