function substr_count( haystack, needle, offset, length ) {	// Count the number of substring occurrences
	// 
	// +   original by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)

	var pos = 0, cnt = 0;

	if(isNaN(offset)) offset = 0;
	if(isNaN(length)) length = 0;
	offset--;

	while( (offset = haystack.indexOf(needle, offset+1)) != -1 ){
		if(length > 0 && (offset+needle.length) > length){
			return false;
		} else{
			cnt++;
		}
	}

	return cnt;
}