Call keydown event base on selected value with jQuery

Question

I want to make an input text numeric only or no base on a user selection from a dropdown (if the user choose Customer Code or Rate Request Id then the textbox is numeric only, if it is Customer Code can write letters). Here is the code that I wrote but is not working, any help? jsfiddle code

<select id="test" class="target">
<option value="custName">Customer Name</option>
<option value="custCode">Customer Code</option>
<option value="rateReqId">Rate Request Id</option>
</select>
<input id="target" type="text" />

and the Javascript code is:

// Numeric only control handler
jQuery.fn.ForceNumericOnly =

function() {
    return this.each(function() {
        $(this).keydown(function(e) {
            var key = e.charCode || e.keyCode || 0;
            // allow backspace, tab, delete, arrows, numbers and keypad numbers ONLY
            return (
            key == 8 || key == 9 || key == 46 || (key >= 37 && key <= 40) || (key >= 48 && key <= 57) || (key >= 96 && key <= 105));
        });
    });
};

$('#test').change(function() {
    var val = this.value;
    switch (val) {
        case "custName":
            $("#target").unbind('ForceNumericOnly')
            break;
        case "custCode":
            alert('inside custCode');
            $("#target").ForceNumericOnly();
            break;
        case "rateReqId":
            break;
        default:
    }
});​

Answer 1

thanks to @thecodeparadox I ended doing the following: demo

html code:

<select id="test" class="target">
<option value="custName">Customer Name</option>
<option value="custCode">Customer Code</option>
<option value="rateReqId">Rate Request Id</option>
</select>
<input id="target" type="text" />

<div id="toolTip" style="border: solid 1px #000; padding: 2px 2px 2px 2px; background-color: #f1f1f1; width: 150px; height: 30px; font-size: 11px; position: absolute; top: 250px;
    left: 130px; display: none;">test
</div>

jquery code:

// Numeric only control handler
jQuery.fn.ForceNumericOnly =

function(selectedFilter) {
    return this.each(function() {
        $(this).keydown(function(e) {

            var key = e.charCode || e.keyCode || 0;
            // allow backspace, tab, delete, arrows, numbers and keypad numbers ONLY
            var result = (
            key == 8 || key == 9 || key == 46 || (key >= 37 && key <= 40) || (key >= 48 && key <= 57) || (key >= 96 && key <= 105));

            if (!result) {
                var tooltip = $('#toolTip');

                if (!tooltip.is(':visible')) {
                    tooltip.text("Numeric values only for " + selectedFilter);
                    tooltip.show().fadeOut(3000);
                }

            }
            return result;
        });
    });
};

$('#test').change(function() {
    var val = this.value;
    var input = $("#target");
    switch (val) {
    case "custName":
        input.val('').unbind();
        break;
    case "custCode":
        input.val('').unbind().ForceNumericOnly("Customer Code");
        break;
    case "rateReqId":
        input.val('').unbind().ForceNumericOnly("Rate Request Id");
        break;
    default:
    }
});​

Actually I dont know if this is the better way to do it or the most effective one, so still open to suggestions

Thanks for the help :)