textbox의 글자수 Check(Byte)

var oldStr, oldCnt;

function checkByte(element, labelID, Count) {
    var onechar;

    var tcount = 0;
    for (k = 0; k < element.value.length; k++) {

        onechar = element.value.charAt(k);

        if (escape(onechar).length > 4) {
            tcount += 2;
        }
        else if (onechar == '\n') {
            tcount += 2;
        }
        else if (onechar != '\r') {
            tcount++;
        }
           
    }
    var Label = eval("document.getElementById('" + labelID+ "')");

    if (tcount > parseInt(Count, 10)) {
        Label.innerHTML = Count;
        element.value = oldStr;
        tcount = oldCnt;
        return false; ;
    }

    oldStr = element.value;
    oldCnt = tcount;

    Label.innerHTML = tcount;

    return true;
}
사용법
onkeyup="return checkByte(this,라벨ID,제한글자수);"