When you use an <apex:... id="..."> component, the id value gets prefixed. The simplest fix is to use the "ends with" ($=) selector:

$("[id$='notes']").doStuff(function () { ... });

When you use an <apex:... id="..."> component, the id value gets prefixed. The simplest fix is to use the "ends with" ($=) selector:

var input = $("[id$='notes']");
var notFound = $("#notes"); // this value is not the literal id

See also:

• Best Practices for Accessing Component IDs
• Using $Component to Reference Components from JavaScript
• $Component