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Similarly within a method, avoid switching between if statements and switch statements and back:

    if (x === y) {
        return 'x';
    }
    switch (x) {
    case z:
        ...
    }
    if (x ...

This is better written with pure if statements.

Continuing this thought process, don't switch between method short circuiting and "The One Return" (with one exception: arg checks):

    if (x) { return a; }
    if (y) { return b; }
    if (z) { r = ... }
    if (!r && t) { r = ... }
    ...
    return r || ...;
    }

In general, logic that changes in style is much harder to read than logic that remains stylistically constant.

8. Pull constants out

If a variable doesn't change within a function or between runs of a function, then it is not a variable with respect to that function. Thus it doesn't belong there (except at the root level).

9. Use the right method for the job

    Instead of                                   Use 
    .attr('data-x')                              .data('x')
    if (x) { $a.show() } else { $a.hide() }      $a.toggle(x) 
    x ? $a.addClass('a') : $a.removeClass('a')   $a.toggleClass('a', x)
   

.bind('click', function () {

.on('click', function () {

    .bind('click', function () {

    .on('click', function () {

Here are the first steps I would take:

this kind of code is error-prone and makes future refactorings harder (and you will change it later).

Here are the first steps I would take (not necessarily in order):

This kind of code is error-prone and makes future refactorings harder (and you will change it later).

6. Remove unused variables

    $select.focus(function(){
        var $me = $j(this),
            previousval = $me.value,
            $previous = $me.find(':selected');
    }).change(function(){
   

Unused variables are dead weight. Every line of code you don't need to write is a line of code that the person looking at this 6 months from now doesn't need to look at and figure out what you were thinking. Unused variables come in several forms:

1. variables in the beginning of your functions (see step 2) that don't get used within the function
2. variables that get exported to an outer scope but do not serve a purpose
3. functions that do not get used
4. event handlers that don't do anything

7. Code that does the same thing should look the same

JQuery has a half dozen ways to bind events (.bind, .on, .click, .live, .delegate, .one). The only one you need is .on. Replace:

.bind('click', function () {

with

.on('click', function () {

and so on.