Question

$(function() {
    function split( val ) {
        return val.split( /,\s*/ );
    }
    function extractLast( term ) {
        return split( term ).pop();
    }
    $( "#names" ).autocomplete({
        source: function(request, response) {
            $.ajax({ url: "<?php echo site_url('update/suggestions'); ?>",
            data: { term: extractLast( request.term )},
            dataType: "json",
            type: "POST",
            success: function(data){
                response(data);
            },
            focus: function() {
                // prevent value inserted on focus
                return false;
            },
            select: function( event, ui ) {
                var terms = split( this.value );
                // remove the current input
                terms.pop();
                // add the selected item
                terms.push( ui.item.value );
                // add placeholder to get the comma-and-space at the end
                terms.push( "" );
                this.value = terms.join( "," );
                return false;
            }
        });
    },
    minLength: 2
    });
});

The above code is replacing the existing selection rather than adding the new selection to the existing one. This is in Codeigniter. The single Autocomplete is working fine.
This is not for multiple input fields it is for adding multiple values to a single input field.

Answer 1

You code has several issues:

• you are not correctly closing the $.ajax function and source option function.
• the minLength: 2 is also misplaced.
• because of previous problems, you got too much closing brackets/parenthesis.

For instance you have:

    source: function(request, response) {
        $.ajax({ url: "<?php echo site_url('update/suggestions'); ?>",
        ...
        success: function(data){
            response(data);
        },
    // missing closings
    focus: function() {

which should be:

    source: function(request, response) {
        $.ajax({
            url: "<?php echo site_url('update/suggestions'); ?>",
            ...
            success: function(data) {
                response(data);
            }
        });   // closes $.ajax function
    },    // closes the 'source' function
    focus: function() {

Check this DEMO with correct syntax. It works correctly (I’ve added an error handler to the ajax to display some static results).