/**
* This function limits the length of input entered into a text field.
* @param obj - input field
* @param max_length - maximum length allowed.
*/
function limitInputLength(obj,max_length){
	var input = obj.value;
	var current_length = input.length;
	if(current_length >= max_length){
		obj.value = input.substring(0,max_length);
	}
}

/*
* This function displays a counter for the number of characters
* that can be entered into a text field.
* @param obj - input field
* @param max_length - maximum length allowed.
* @param divElement - where the characters left message will be displayed.
*/
function displayCounter(obj,max_length,divElement){
	var charssofar = obj.value.length;
	var left = max_length - charssofar;
	
	if(left < 0){
		document.getElementById(divElement).innerHTML = "characters left : <font color='red'>" + left + "&nbsp;&nbsp;</font>";
	}
	else{
		document.getElementById(divElement).innerHTML = "characters left : " + left + "&nbsp;&nbsp;";
	}
}

/**
* This function only lets the user enter numeric characters.
* @param obj - input field.
*/
function numbersOnly(obj){
	obj.value=obj.value.replace(/[^0-9]/g,'');
}