//extract front part of string prior to searchString
function getFront(mainStr,searchStr){
	foundOffset = mainStr.indexOf(searchStr)
	if (foundOffset == -1) {
		return null;
	}
	return mainStr.substring(0,foundOffset)
}
// extract back end of string after searchString
function getEnd(mainStr,searchStr) {
	foundOffset = mainStr.indexOf(searchStr)
	if (foundOffset == -1) {
		return null;
	}
	return mainStr.substring(foundOffset+searchStr.length,mainStr.length)
}
// insert insertString immediately before searchString
function insertString(mainStr,searchStr,insertStr) {
	var front = getFront(mainStr,searchStr)
	var end = getEnd(mainStr,searchStr)
	if (front != null && end != null) {
		return front + insertStr + searchStr + end
	}
	return null;
}
// remove deleteString
function deleteString(mainStr,deleteStr) {
	return replaceString(mainStr,deleteStr,'');
}
// replace searchString with replaceString
function replaceString(mainStr,searchStr,replaceStr) {
	var front = getFront(mainStr,searchStr)
	var end = getEnd(mainStr,searchStr)
	if (front != null && end != null) {
		return front + replaceStr + end
	}
	return null
}

function replaceStr(string) {
	//double any single quotation mark
	var pattern = /\'/g; 
	var newString = string.replace(pattern, "''"); 
	return newString; 
}

function trim(str) { 
        // Strip leading and trailing white-space 
        return str.replace(/^\s*|\s*$/g, "");
}