Problem while using autocomplete.js for Numeric data field

Hi,
I have an autocomplete implemented for a Numeric text field. Its working however for multiple key stroke it throws error.

Example in my text box If I am looking for any number that starts with 1 , I type 1 and I get list of the numbers that starts with 1.
However, if my number is 123 and then after 1 I type 2 i get following error
Object does not support this property or method in autocomplete.js file ( I have highlighted the area where I get error)

function matchSubset(s, sub) {
		if (!options.matchCase) 
			s = s.toLowerCase(); 	
	var i = s.indexOf(sub);
		if (options.matchContains == "word"){
			i = s.toLowerCase().search("\\b" + sub.toLowerCase());
		}
		if (i == -1) return false;
		return i == 0 || options.matchContains;

2. I get only 10 records however, table has 100 records...Why ??

Best Regards,
Rohan Laghate