function sms_calcleft() {
	var sms_total_chars=100;
	var formElement = document.getElementById("sms_form");
	var numleft=sms_total_chars-document.sms_form.msg.value.length;
	formElement.left.value = numleft;
	formElement.used.value = formElement.msg.value.length;
	if(numleft<0) formElement.send.disabled=true;
	else formElement.send.disabled=false;
}
function addEvents()
{
    var submitElement = document.getElementById("sms_submit");
    submitElement.onclick = function (e)
    {
    	submitElement.disabled = true;
    }
	var textElement = document.getElementById("sms_text");
    textElement.onkeyup = function (e)
    {
    	sms_calcleft();
    }
}
window.onload = function(e)
{
	sms_calcleft();
	addEvents();
}