var CharLimit = 2500; // The limit

function CheckChar(id, divCount)
{
    var txtarea = document.getElementById(id); // The textarea to limit
    var divCount = document.getElementById(divCount);//The div to show the characters left
    var CharEntered = txtarea.value; // The characters entered
    var CharCount = CharEntered.length; // The characters length

    if(CharCount >= CharLimit)
    {
        txtarea.value = CharEntered.substring(0, (CharLimit));
        divCount.innerHTML = 0;
    }
    else
    {
        divCount.innerHTML = (CharLimit - CharCount);
    }
}