var Left = function(str, n){
	if (n <= 0)
	    return "";
	else if (n > String(str).length)
	    return str;
	else
	    return String(str).substring(0,n);
}

var Right = function(str, n){
    if (n <= 0)
       return "";
    else if (n > String(str).length)
       return str;
    else {
       var iLen = String(str).length;
       return String(str).substring(iLen, iLen - n);
    }
}

// Trims a string
var Trim = function(stringToTrim) {
	return stringToTrim.replace(/^\s+|\s+$/g,"");
}

function AmountValid(Desc) {
	if (Left(document.PayPalFormOpenAmt.amount.value, 1)=='$') {
		document.PayPalFormOpenAmt.amount.value = Right(document.PayPalFormOpenAmt.amount.value, String(document.PayPalFormOpenAmt.amount.value).length-1);
	}
	
	if (document.PayPalFormOpenAmt.amount.value=='' || !IsFloat(document.PayPalFormOpenAmt.amount.value)) {
		alert('Please enter a valid amount');
		return false;
	}
	
	if (document.PayPalFormOpenAmt.comments.value=='comments') {
		document.PayPalFormOpenAmt.item_name.value = Desc + ': ' + '[no comments]';
	} else {
		document.PayPalFormOpenAmt.item_name.value = Desc + ': ' + document.PayPalFormOpenAmt.comments.value;
	}
	
	return true;
}