Question

I want to detect if this text field is empty or not and then run some code based on that.

Question is: how can I run the code only once …and then run it once again each and every time that the state of the text field changes during one focus

• Different states being empty or not empty.

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To further elaborate:

( The most important part in these jsfiddle’s are shown in the console. )

• Here is a jsfiddle of a code that executes the code every
  time you keyup (Not what I want. Just the initial code. ).

  $('input').on("keyup", function() {
  
      var val = $(this).attr('value'),
          previous = $(this).prev();
  
      if ( val === '' ) {
          console.log('Empty');
      }
      else if ( val !== '' ) {
          console.log('Text');
      }
  
  });
  

• and Here is a jsfiddle of a code that executes the code once
  per focus (This is somewhat near to what I want).

  What it is still missing, and what I can’t seem to get done, is to basically run the code once again each and every time that the state
  changes during that one focus. How could I do that?

  $('input').on("focus", function() {
  
      $('input').one("keyup", function() {
  
          var val = $(this).attr('value'),
              previous = $(this).prev();
  
          if ( val === '' ) {
              console.log('Empty');
          }
          else if ( val !== '' ) {
              console.log('Text');
          }
  
      });
  
  });
  

Answer 1

You need to use a plugin called jQuery Text Change from ZURB. Does everything you want and more, also has a trigger action called ‘hastext’ and ‘notext’, take a look at:

http://www.zurb.com/playground/jquery-text-change-custom-event

there are also demos there.

I made this for you (using that plugin).

LIVE DEMO:

http://jsfiddle.net/oscarj24/UtwNz/

Hope this helps 🙂