Question

How can I make a div show or hide based on a form inputs value. Specifically if It’s value is positive. I want it to show one div. Otherwise I want it to show another div.

Here is the more complex thing that I actually want
. If form1 is greater than 10,000 and form2 is less than zero. Show this first div(if both are met). If condition for form 1 is met and form two is not met(form 2 is a positive number) show this second div.If anything else(neither are met or form 1 not met(9000) but form two is(a negative number) show this third div

Answer 1

Lets assume you have the following to divs:

   <div class="show_when_more">
     Foo 
  </div>

   <div class="show_when_less">
     Bar
   </div>

And the following input you want to be watching:

   <input type="text" class="to_watch"/>

Then the following Javascript would do it for you (you would require jquery for this to work):

   $('input.to_watch').on('change', function(){
       if($(this).val()>=1000){
           $('div.show_when_more').css('display', 'block');
           $('div.show_when_less').css('display', 'none');
       } else {
           $('div.show_when_more').css('display', 'none');
           $('div.show_when_less').css('display', 'block');
       }
    });

This would also work with any other type of selector (eg by id, by element type, etc)