js中实现输入框输入字数提示

function countChar()
    {
     var count=100-document.getElementById("remark1").value.length;
     if(count>0){
         document.getElementById("counter").innerHTML = "您还可以输入"+count+"个字";
         $("#counter").css("color","black");
         flag= true;
     }else{
         document.getElementById("counter").innerHTML="您输入的字数已经超出100个字！";
         $("#counter").css("color","red");
         flag= false;
     }
    }

    <textarea  id="remark1" style="width: 357px; height: 76px;" onkeydown=‘countChar();‘ onkeyup=‘countChar();‘></textarea>